Adam is 36 years old.
Bryan is 21 years old.
A few years ago, Adam was 4 times as old as Bryan.
- How many years ago was Adam 4 times as old as Bryan?
- How old was Adam then?
|
Adam |
Bryan |
Difference |
Before |
4 u |
1 u |
3 u |
Change |
+ ? |
+ ? |
|
After |
36 |
21 |
15 |
(a)
For Adam to be 4 times as old as Bryan,
Bryan's age = 1 u
Adam's age = 4 u
Difference in their age
= 4 u - 1 u
= 3 u
Age difference between Adam and Bryan
= 36 - 21
= 15
3 u = 15
1 u = 15 ÷ 3 = 5
Number of years' ago that Adam was 4 times as old as Bryan
= 21 - 5
= 16
(b)
Adam's age 16 years ago
= 4 u
= 4 x 5
= 20
Answer(s): (a) 16; (b) 20