# Algebra - problems - page 90

1. Ten boys Ten boys chose to go to the supermarket. Six boys bought gum and nine boys bought a lollipop. How many boys bought gum and a lollipop?
2. On line On line p: x = 4 + t, y = 3 + 2t, t is R, find point C, which has the same distance from points A [1,2] and B [-1,0].
3. The farmer The farmer had 140 sheep. For the next year, she decided to change the number of sheep in ratio 10: 7. How many sheep will he have then?
4. Two resistors Two resistors when they give 25 ohms in series and 4 ohms in parallel what the values of
5. Exponential warm Suppose that a body with temperature T1 is placed in surroundings with temperature T0 different from that of T1. The body will either cool or warm to temperature T(t) after time t, in minutes, where T(t)=T0 + (T1-T0)e^(-kt) . If jello salad with 30 degre
6. Circle described The radius of the circle described to the right triangle with 6 cm long leg is 5 cm. Calculate the circumference of this triangle.
7. Digit sum How many are three-digit numbers that have a digit sum of 6?
8. Height as diameter of base The rotary cylinder has a height equal to the base diameter and the surface of 471 cm2. Calculate the volume of a cylinder.
9. Rectangular garden The sides of the rectangular garden are in ratio 1: 2. The diagonal has a length of 20 meters. Calculate the area and perimeter of the garden.
10. Sum of inner angles Prove that the sum of all inner angles of any convex n-angle equals (n-2) . 180 degrees.
11. Map scale The rectangular plot has in a scale of 1: 10000 area 3 cm2 on the map. What content does this plot have on a 1:5000 scale map?
12. Water current speed. Two cities along the river are 100 km apart. The powerboat downstream runs for 4 hours, upstream for 10 hours. Determines the river's current speed.
13. Bricklayers Seven bricklayers will build the house in 630 days. How many bricklayers do we need to take after 150 days to complete the building for (additional) 336 days?
14. Sales off The price has decreased by 20%. How many percents do I have to raise the new price to be the same as before the cut?
15. Highway tunnel The highway tunnel was built from two ends in the north-south direction. The average daily performance of the "northern party" rasters was higher than the average daily power of the "southern party" of the rasters. After 55 business days, both parties met.
16. Father 7 Father is 6 times older than his son. After 4 years, the father will only be 4 times older. What are their present ages?
17. Edges or sides Calculate the cube volume, if the sum of the lengths of all sides is 276 cm.
18. Acid evaporation How many kilograms of water do we have to evaporate from 100 kg of 32% acid to make it 80% concentration?
19. Diagonals of the rhombus How long are the diagonals e, f in the diamond, if its side is 5 cm long and its area is 20 cm2?
20. Water reservoir One drain hole emptied the water from the tank for 20 hours, with the second drain for 30 hours. How long will the water drain from this tank if we open two drains simultaneously?

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