Question

The total mass of Abdul and his baby brother is 15.25kg . The mass of Abdul and his father is 72.25kg . The mass of Abdul's father is 13 times as heavy as Abdul's baby brother. What is Abdul's mass?

Answer 1

a+b=15.25

a+f=72.25, since f=13b

a+13b=72.25  so now we have two equation in two variables...

a+13b=72.25 and a+b=15.25  so we can say:

(a+13b=72.25)-13(a+b=15.25)

a+13b-13a-13b=72.25-198.25

-12a=-126

a=10.5 kg

So Abdul's mass is 10.5 kilograms.