Equation - examples - page 47
- CuSO4 mixture
How many grams of solid CuSO4 we have to add to 450g of 15% CuSO4 solution to produce a 25% solution?
- Temperature 2
Sunday's high temperature was 3 degrees higher than Saturday's. On Monday, the temperature fell 5 degrees, then rose 7 degrees on Tuesday and 4 more on Wednesday. Then it fell 17 degrees to a record low of 31 on Thursday. What was the temperature on Saturd
- My father
My father has a big farm. 6/8 of it were planted with mango trees, 1/2 of the remainder are guava trees and the rest 10 trees are santol trees. What is the number of all trees?
- I think
I think a number. When I multiply it by five, and after that I subtract 477, I get the same number as if I multiplied it twice. What number do I think?
- The train
The train passed the observer in the 20s and passed through a 1500m tunnel in 2 minutes. Calculate the speed (km/h) and train length.
- Car driver
The car driver is in town A and is scheduled to be in town B at a specified hour. If it travels at an average speed of 50km/h, it will arrive in city B 30 minutes later. But if he travels at an average speed of 70km/h, he would arrive half an hour earlier
- Two pipes
How long will the pool be filled with a double supply pipe if it takes the pool to fill the first pipe by 4 hours longer and the second pipe 9 hours longer than both pipes open at the same time?
- Three painters
One painter would have painted the fence for 15 hours, the second in 12 hours. The plot had to be painted in four hours, so they called the third one, and all worked together. For what time would the third painter paint fence the fence alone?
How many ml 30% of peroxide (H2O2) should be poured into 100ml H2O to give a 20% solution?
- Diagonals of a rhombus 2
One diagonal of a rhombus is greater than other by 4 cm . If the area of the rhombus is 96 cm2, find the side of the rhombus.
The seamstress cut the fabric into 3 parts. The first part was the eighth fabric, the second part was three-fifths of the fabric and the third part had a length of 66 cm. Calculate the original length of the fabric.
One-eighth of the trees in the fruit plant in winter froze and one-twelfth of damaged disease and pests. Healthy trees remained 152. Is it enough to supply 35 trees to restore the original number of trees in the orchard?
- Sale discount
The product was discounted so that eight products at a new price cost just as five products at an old price. How many percents is the new price lower than the old price?
- Our house
Our house would paint four painters in 14 days. How long could it paint five painters? How long will it take if two other painters will come to help after 5 days?
Mother bought 21 desserts on the occasion of Mirka's birthday one tips was 9 CZK and the kremlin cost 12 CZK. For all desserts, she paid 213 CZK. How many kremlins and how many tips mums did buy?
- Average age
The company of five people has an average age of 46 years. The average age of the first four is 43 years. How many years has the fifth member of this company?
- Exponential equation
Determine the value of having y in the expression (3^y): (4^-1)=36.Y is a natural number greater than zero.
- Pupil age
I am a pupil of the primary school, I spent 1/4 of my age on the exercise of parents with children, 1/3 on drawing, 1/6 on flute. I did not have a ring for the first three years of my life and never went to two rings at once. How old am I?
- Two diggers
Two diggers should dig a ditch. If each of them worked just one-third of the time that the other digger needs, they'd dig up a 13/18 ditch together. Find the ratio of the performance of this two diggers.
3400 eggs sliced hens for February and March. We have to calculate how many hens can make 3400 eggs when one hen give 2 eggs a day for 59 days.
Do you have a linear equation or system of equations and looking for its solution? Or do you have quadratic equation?