Question

consider the ratio 12:5 if this ratio has to be reduced by 20% which common number should be added to both the numerator and denominator?​

Answer 1

Answer:

Consider

12/5. This has to be reduced by 20%. This means we have to consider 80% of this number. (Why?) Thus we must get

$12 \div 5 \times 80 \div 100 = 48 \div 25$

We have to find a such that

12+ a / 5+ a = 48/25

.

Cross multiplying, we obtain

25(12+a)=48(5+a).

This simplifies to

48a−25a=(25×12)−(48×5), or 23a=60.

Hence,

a= 60/23

If we add 60/23 to both terms of 12:5 we get a ratio which is 20% less than the original ratio.