# Equation - examples - page 42

1. Modulo Find x in modulo equation: 47x = 4 (mod 9) Hint - read as: what number 47x divided by 9 (modulo 9) give remainder 4 .
2. Diamond diagonals Calculate the diamonds' diagonals lengths if the diamond area is 156 cm square and the side length is 13 cm.
3. Suzan Susan's age will be after 12 years four times as much as twelve years ago. How old is Susan now?
4. Soaps Each box has the same number of soaps. A quarter of all boxes contain only white soaps, and in each of the remaining 120 boxes there are always half the white soaps and half the green. White soaps total 1200. (a) the number of all soap boxes; (b) the sma
5. Lighthouse The man, 180 cm tall, walks along the seafront directly to the lighthouse. The male shadow caused by the beacon light is initially 5.4 meters long. When the man approaches the lighthouse by 90 meters, its shadow shorter by 3 meters. How tall is the lightho
6. Paul earned Paul earned 300 Kč in one hour, Václav 1/3 more than Paul. Václav worked 60 hours, which is 1/3 fewer hours than Paul worked. How many percents less earned Paul an hour than Václav? How many hours did Paul more than Václav? How much did Paul earn more t
7. Pears There were pears in the basket, I took two-fifths of them, and left six in the basket. How many pears did I take? If 5x + x² > 100, then x is not
9. Summands Find two summands of the number 42, so that its product is minimized.
10. Bicycle gears The toothed wheel on the bicycle pedal has 40 teeth, the wheel on the rear wheel has only 16 teeth. How many times does the rear wheel turn if the pedals rotate 50 times?
11. Number unknown Adela thought the two-digit number, she added it to its ten times and got 407. What number does she think?
12. Children The group has 42 children. There are 4 more boys than girls. How many boys and girls are in the group?
13. House numbering The residential house has three entrances numbered even numbers, successive immediately behind. The sum of the two numbers on the outside entrances is 68. Calculate the middle of these three numbers.
14. Digit sum The digit sum of the two-digit number is nine. When we turn figures and multiply by the original two-digit number, we get the number 2430. What is the original two-digit number?
15. Surface area of the top A cylinder is three times as high as it is wide. The length of the cylinder’s diagonal is 20 cm. Find the surface area of the top of the cylinder.
16. Percentages 5 \$5.25 is 7 1/2% of what number? Several pieces of bread were in the store. Half of them plus a half of bread bought a cookbook. Of the remaining bread, half of it plus half of the bread was bought by Mr. Novák. The last bread was bought by Ms. Small. How many breads were in the store at.
18. Clouds Approximately at what height is the cloud we see under an angle of 26°10' and see the Sun at an angle of 29°15' and the shade of the cloud is 92 meters away from us?
19. Ľé sweets There are 20 sweets in the bag. Some are chocolate, other coconuts, and the remaining marzipan. Chocolate is 4 times more than coconut. Marzipan's less than chocolate. How much is in a bag of coconut sweets?
20. Garden The garden around the new majer is divided as follows: 35% vegetable, 30% fruit orchards, 10% flowers and the remaining 120 m2 are lawns. What is the total area of the garden?

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