# Equation - 7th grade (12y) - examples - page 3

1. Workers
Two workers fulfill a certain task when working together for 5 days, the first if he worked himself done work in 13 days. How many days will do whole job a second worker?
2. Lentilka
Lentilka made 31 pancakes. 8 don't fill with anything, 14 pancakes filled with strawberry jam, 16 filled with cream cheese. a) How many Lentilka did strawberry-cream cheese pancakes? Maksik ate 4 of strawberry-cream cheese and all pure strawberry pancake
3. Acid
The barrel is 199 litres of 38% acid. How many percent acid occurs when 61 litres revoke and replace it with the same amount of water?
4. Tape
Video is 153% more expensive than tape recorder. How many percent is tape recorder less expensive than video?
5. Salary raise
The monthly salary was 620 Eur. During the year it was raised to 727 Eur. Calculate the month from salary was increased that employee earned 7547 Eur during the whole year.
6. Garden
Father dig up the garden in 9 hours. Son in 13 hours. How many hours take dig up the garden together?
7. Number ratio
Calculate two positive numbers that its ratio is 6:6 and difference was 0.
8. Parquet floor
Three workers laid parquet floor for 2.301 hour. The first one would do this work alone 7 hours, the second in 6 hours. For how many hours would fulfill this work the third worker, if he worked alone?
9. Seedcake
Seedcake costs 44 cents. How many minimum seedcakes we must buy that we can pay in cash only whole euros?
During the spring cleaning ladies going to wash windows. Mother takes wash all the windows 5 hours, the grandmother 3 times longer and Paula wash all windows in 2 hours. How many hours will spend washing the windows this "women's team" if working togethe
11. Triangles
Equilateral triangle with side 40 cm has the same perimeter as an isosceles triangle with arm of 45 cm. Calculate the base x of an isosceles triangle.
12. Vinegar
We must dilute 16 liters of 8.8% aqueous vinegar to 4.1% one. How much water is necessary to add?
13. Expression
If it is true that ? is:
14. Motion
From two different locations distant 232 km started against car and bus. The car started at 5:20 with average speed 64 km/h. Bus started at 7:30 with average speed 80 km/h. When they meet? How many kilometers went the bus?
15. Unknown x
If we add to unknown number 21, then divide by 6 and then subtract 51, we get back an unknown number. What is this unknown number?
16. Clock
What time is now, if the time elapsed after noon is 2/10 of time that elapses before midnight?
17. Barrel 3
Barrel with water has a weight 118 kg. When we get off 75% of water it has a weight 35 kg. How many kg has empty barrel?
18. Trio
Trio of workers earn 750 euros. Money divided by the work that each of them made​​. First received twice as the second, the second received three times more than the third. How many got everyone from workers?
19. Trains
On double track line between stations K and M went against each other two trains. The first train passed the distance between stations for 3.5 hours, the second, which had an average speed of 12 km/h more passed for 3.05 hours. Calculate the distance betw
20. Rhombus
Internal angles of rhombus is in ratio 2:3. How many times is the shorter diagonal longer than side of rhombus?

Do you have an interesting mathematical example that you can't solve it? Enter it, and we can try to solve it.

To this e-mail address, we will reply solution; solved examples are also published here. Please enter e-mail correctly and check whether you don't have a full mailbox.

Do you have a linear equation or system of equations and looking for its solution? Or do you have quadratic equation?