# Expression of a variable from formula - examples - page 15

1. Vacation
Tomas spent 60% of his savings for his weekly vacation. He was 32 € left. How many euros did he have before vacation?
2. Square s3
Calculate the diagonal of the square, where its area is 0.49 cm square. And also calculate its circumference.
3. The cylinder base
The cylinder with a base of 8 dm2 has a volume of 120 liters. From a cylinder fully filled with water, 40 liters of water was removed. At what height from the bottom /with precision to dm/ is the water level?
4. Cows
Agricultural cooperative has increased the number of housed cows by 14% to 285 units. By how many cows increased agricultural cooperative the number of cows?
5. Cube walls
Find the volume and surface area of the cube if the area of one wall is 40cm2.
6. Wine
A bottle of wine costs 21 euros; and wine is 20 times more expensive than a bottle. How much a bottle cost?
7. Trucks
Three lorries droved bricks. One drove n bricks at once, second m less bricks than the first and third 300 bricks more the first lorry. The first lorry went 4 times a day the largest went 3 times a day and the smallest 5 times a day. How many bricks br
8. Tank diameter
A cylindrical tank has a volume of 60 hectoliters and is 2.5 meters deep. Calculate the tank diameter.
9. Holidays - on pool
Children's tickets to the swimming pool stands x € for an adult is € 2 more expensive. There was m children in the swimming pool and adults three times less. How many euros make treasurer for pool entry?
10. Hypotenuse
Calculate the length of the hypotenuse of a right triangle if the length of one leg is 4 cm and its content area is 16 square centimeters.
11. Perimeter to area
Calculate the area of a circle with the perimeter 15 meters.
The surface of the sphere is 60 cm square. Calculate its radius; result round to tenth of cm.
13. Table
The circumference of the rectangle table is 420 cm. Length to width ratio is 5:2 . Calculate table dimensions and dimensions reduced in the ratio 3:5
14. RT perimeter
The leg of the rectangular triangle is 7 cm shorter than the second leg and 8 cm shorter than the hypotenuse. Calculate the triangle circumference.
15. Trapezoid - central median
The central median divides the trapezoid into two smaller trapezoids. Determines the ratio of their contents.
16. Raspberries
Dano had 20 raspberries. John had 90% more raspberries than Dano. Determine how many raspberries have Dano and Juraj together.
17. Fifth member
Determine the fifth member of the arithmetic progression, if the sum of the second and fifth members equal to 73, and difference d = 7.
18. Rectangle 35
Find the area of a rectangle when the diagonal is equal to 30 cms and the width is double the length.
19. Regular n-gon
In a regular n-angle polygon the internal angle is 144 degrees. Find the number n indicating the number of sides of this polygon.
20. Arithmetic progression
In some AP applies: 5a2 + 7a5 = 90 s3 = 12 Find the first member a =? and difference d = ?

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