Question

5. There are two barrels of gasoline in the warehouse. There are 21 kilograms in barrel A and 5 kilograms in barrel B. After adding the same quality gasoline, the gasoline in barrel A is 3 times that in barrel B. Now there are two barrels A and B. How many kilograms of gasoline are in the barrel?

Answer 1

Suppose that we add x kilograms in barrel A and 5 kilograms in barrel B. Then

$$21+x=3(5+x)$$

$$21+x=15+3x$$

$$2x=6$$

$$x=3$$

$$21+3=24$$

$$5+3=8$$

There are 24 kilograms in barrel A and 8 kilograms in barrel B.