Question

Randy is now four years older than Eric. Five years ago Randy was twice as old as Eric. How old was ready five years ago?

Answer 1

Answer: Five years ago Randy was 8 years old

Explanation:

We are told that now Randy is four years older than Eric:

`R=E+4` (1)

Then, we are told that five years ago Randy was twice as old as Eric:

`R-5=2(E-5)` (2)

At this point we have a system with two equations and two unknowns.

Let's begin by substituting (1) in (2):

`E+4-5=2(E-5)` (3)

`E+4-5=2E-10` (4)

Isolating
`E`:

`E=9` (5) This is Eric's current age

Substituting (5) in (1):

`R=9+4` (6)

`R=13` (7) This is Randy's current age

This means that five years ago Randy's age was 8 years old:

`R-5=13-5=8`