Word Problem

Question

Marcos is 25 years old. The difference between his age and 5 x 10^-2 times is sister age is 12/0.5. How many years apart are Marcos and his siter's age

Answer 1

12/0.5 is 24. 

 

So 5 x 10^-2 times is sister age is 1.

 

5 x 10^-2 = .05, which is 1/20.   If 1/20 times his sister's age is 1, then 1/20 is the reciprocal of her age.  That means that her age is 20.