Review Chapter

A zoo has 6 tigers, 7 dolphins, 3 chickens and 2 spiders. What is the sum of the legs of all animals?

• 34 legs

• 38 legs

• 60 legs

• 46 legs

Find the value of 18 + 27 - 36 - 45 - 54 - 63 + 72 + 81

A number is subtracted to 7. The diference is then multiplied by 7. The product is added to 7. Lastly, the sum is divided by 7. The answer is 7. What is the value of this number?

Carson gave 20 marbles to his cousin. He gave another 26 marbles to his friend before he bought another 10 marbles. He then had 14 marbles. How many marbles did Carson have at first?

(gave: đã cho; bought: đã mua; at first: ban đầu)

In the following picture, every adjacent four cells have a sum of 20. Find the value of X + y.

(adjacent four cells: bốn ô liền kề nhau)

• 14

• 12

• 10

• 6

A fruit store had a basket of oranges. They sold half of the oranges in the first day. In the 2nd day, they sold 25 oranges and threw away 7 rotten oranges. They foud that there were 50 oranges left. How many oranges does the store have at first?

(sold: đã bán; threw away: đã ném đi; half of: một nửa; left: còn lại: at first: ban đầu)