# Expression of a variable from the formula - 7th grade (12y) - math problems

#### Number of problems found: 234

• Cube containers Replace the two cube-shaped containers with 0.8 dm and 0.6 dm edges with a single cube-shaped one so that it has the same volume as the two original ones together. What is the length of the edge of this cube?
• Volume per time How long does fill take for a pump with a volume flow of 200 l per minute fill a cube-shaped tank up to 75% of its height if the length of the cube edge is 4 m?
• Gardens The area of the square garden is 3/4 of the area of the triangular garden with sides of 80 m, 50 m, 50 m. How many meters of the fence do we need to fence a square garden?
• Six painters Six painters paint an area of 120 m2 in 4 hours. How long does it take for 12 painters to paint 480 m2 with the same performance?
• Thousand balls We have to create a thousand balls from a sphere with a diameter of 1 m. What will be their radius?
• Extending square garden Mrs. Petrová's garden had the shape of a square with a side length of 15 m. After its enlargement by 64 m2 (square), it had the shape of a square again. How many meters has the length of each side of the garden been extended?
• Height The content of the triangle is 35 cm2. The length of the base is 10 cm. Determine the length of the height on the base.
• Similar triangles Triangle A'B'C 'is similar to triangle ABC, whose sides are 5 cm, 8 cm, and 7 cm long. What is the length of the sides of the triangle A'B'C ' if its circumference is 80 cm?
• Cylinder container The cylindrical container with a diameter of 1.8 m contains 2,000 liters of water. How high does the water reach? How many times does the surface of a sphere decrease if we reduce its radius twice?
• Save trees 25 tons of old paper will save 1,600 trees. How many tons of paper is needed to save the 32 trees in the park?
• Aquarium height How high does the water in the aquarium reach, if there are 36 liters of water in it? The length of the aquarium is 60 cm and the width is 4 dm.
• Cube surfce2volume Calculate the volume of the cube if its surface is 150 cm2.
• The cube The cube has a surface area of 216 dm2. Calculate: a) the content of one wall, b) edge length, c) cube volume. The surface of the regular quadrilateral prism is 8800 cm2, the base edge is 20 cm long. Calculate the volume of the prism
• Second side Calculate the length of the other side of the rectangle if its circumference is 60 cm and one side is 10 cm long.
• Age of family The age of father and son is in the ratio 10: 3. The age of the father and daughter is in ratio 5: 2. How old are a father and a son if the daughter is 20?
• Interior angles Calculate the interior angles of a triangle that are in the ratio 2: 3: 4.
• The farmer The farmer calculated that the supply of fodder for his 20 cows was enough for 60 days. He decided to sell 2 cows and a third of the feed. How long will the feed for the rest of the peasant's herd last?
• Library New books were purchased for the library. Five-eighths were professional books, one-fifth were encyclopedias, and 231 books were dictionaries. How many professional books were there?

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