[Question]1,800 fish swim westward, 3,200 swim eastward, and 500 swim north. What is the number of fish left in the sea, if fishers catch 2/5 of the fish that swam eastward and 3/4 of the fish that swam westward?
[Answer]When fishers caught 3 / 4 of the fish that swam westward, their total number reduced by 3 / 4 * 1800 fish = 1350. The total number of fish that remained from the total number that swam eastward is 1800 fish - 1350 fish = 450 fish. If fishers caught 2 / 5 of the fish that swam eastward, their total number reduced by 2 / 5 * 3200 fish = 1280 fish. 3200 fish - 1280 fish = 1920 fish remained in the sea from the number that swam westward. The total number of fish in the sea after fishers caught some is 500 of the number that went north + 450 of the fish that swam westward + 1920 of the fish that swam eastward = 2870 fish. The answer is 2870.

[Question]Aida has twice as many dolls as Sophie, and Sophie has twice as many dolls as Vera. How many dolls do Aida, Sophie, and Vera have combined if Vera has 20 dolls?
[Answer]If Sophie has twice as many dolls as Vera, then she has 2 * 20 dolls = 40 dolls. Aida has 2 * 40 dolls = 80 dolls, twice the number Sophie has. In total, they have 80 dolls + 40 dolls + 20 dolls = 140 dolls. The answer is 140.

[Question]Mary and Mike are sharing a jar of paint. Mary paints a dragon using 3 square feet worth of paint. Mike paints a castle using 2 square feet more paint than Mary used on her dragon. They both then work together to paint the biggest sun possible. If there was originally enough paint in the jar to cover 13 square feet, how many square feet of paint can be used to paint the sun?
[Answer]The castle uses 3 + 2 = 5 square feet of paint. The sun uses 13 - 3 - 5 = 5 square feet of paint. The answer is 5.

[Question]A 10 meters yarn was cut into 5 equal parts. If 3 parts were used for crocheting, how long was used for crocheting?
[Answer]
Each part is 10 / 5 = 2 meters long. Therefore, 2 x 3 = 6 meters of yarn were used for crocheting. The answer is 6.