Question

Sam is 3 times as old as Rob. If 15 is subtracted from Sam's age and 13 is added to Rob's age, their ages will be equal. How old is each now?

Answer 1

If Rob is R years old then Sam is 3R years old.

Subtract 15 from Sam’s age: 3R-15 and add 13 to Rob’s age: R+13.

These are equal:

3R-15=R+13,

2R=28, R=14 and S=3R=3×14=42.

So Sam is 42 years old and Rob is 14 years old.