# Expression of a variable from formula - examples - page 13

- Chairs

Determine the number of seats in the seventh row and ninth row, if 3rd row has 14 seats and in every next row of seats has five more than the previous row. - Cuboid

Cuboid has a surface of 516 cm^{2}. Side a = 6 cm and b = 12 cm. How long is the side c =? - Difference AP

Calculate the difference of arithmetic progression if the sum of its first 19 members Sn = 8075 and the first member is a_{1}= 20 - Orchard

3/5 of the trees in the orchard are apples, 1/3 are cherries and the remaining five trees are pear. How many trees are in the orchard? - Midpoints

Triangle ABC with sides a = 5 cm, b = 3 cm, c = 40mm has a midpoint of K, L, M. How many centimeters is long perimeter of parallelogram KBLM? - Euros

Peter spent a quarter of his pocket saving. He has 9 euros now in his wallet . How many euros spent? - Circle's chords

In the circle there are two chord length 30 and 34 cm. The shorter one is from the center twice than longer chord. Determine the radius of the circle. - Cyclist vs boat

The cyclist wants to ride a short distance by boat, but when he stops at the pier, the boat does not pick up passengers yet and is preparing to leave. The cyclist decides that the boat will catch up at the next stop. The stop is 12km far along the water an - Apples 2

Dried apples contain 15% water. Fresh apples contain 80% water. How many kg of apples we need buy in order to get 3 kg of dried apples? - Diagonals of a rhombus

One of the diagonals of a rhombus is twice as the other. If the sum of the lengths of the diagonals is 24, find the area of the rhombus. - Truncated cone 3

The surface of the truncated rotating cone S = 7697 meters square, the substructure diameter is 56m and 42m, determine the height of the tang. - Four integers

Fnd four consecutive integers so that the product of the first two is 70 times smaller than the product of the next two. - Arm-leg

Calculate the length of the base of an isosceles triangle with a circumference 224 cm if the arm length is 68 cm. - The swing

To swing the two girls. Aneta weight 45 kg and Simon 35 kg weight. How far should sit Simon from the middle of swing so it is balanced, if we know that Aneta is sitting at distance 1,5m? How far are girls sitting apart? - Wall height

Calculate the surface and volume of a regular quadrangular pyramid if side a = 6 cm and wall height v = 0.8dm. - Equilateral triangle

The equilateral triangle has a 23 cm long side. Calculate its content area. - Square

Danov's father has a square of 65.25 milligram square of wire with a diagonal. How will the square be big when one mm weighs 7 mg? - Cylinder

In a 1-meter diameter cylinder is 1413 liters of water, which is 60% of the cylinder. Calculate the cylinder height in meters, do not write the units. The resulting value round and write as an integer. - Unknown number 4

I think number. When I divided its square root by its 1/9, I get a number 1. What number am I thinking? - Surface of cuboid

Find the surface of the cuboid if its volume is 52.8 cm^{3}and the length of its two edges is 2 cm and 6 cm.

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