Question

What should be added to both 12 and 21 so that they are in the ratio 5:8?​

Answer 1

Answer:

3

Step-by-step explanation:

(12+x)/(21+x)=5/8

Cross multiply

(12+x)*8=(21+x)*5

96+8x=105+5x

Subtract 96 from both sides

8x=5x+9

Subtract 5x from both sides

3x=9

Dividing both sides by 3, we get x=3