Abi will be 51 years old in 6 years' time. Now, Mary's age is 23 of Abi's age. What was Mary's age when she was 4 years less than 80% of Abi's age?
| |
Mary |
Abi |
Difference |
| Before |
4 p - 4 |
5 p |
1 p + 4 |
| Change 1 |
+ ? |
+ ? |
|
| After 1 (Now) |
2 u |
3 u |
1 u |
| Change 2 |
+ 6 |
+ 6 |
|
| After |
2 u + 6 |
51 |
|
Abi's age in 6 years' time = 3 u + 6
3 u + 6 = 51
3 u = 51 - 6
3 u = 45
1 u = 45 ÷ 3 = 15
Difference between Abi's age and Mary's age
= 1 u
= 15
80% =
80100 =
45 Difference in Abi's age and Mary's age at first
= 5 p - (4 p - 4)
= 1 p + 4
The difference in age between Abi and Mary remains unchanged.
1 p + 4 = 15
1 p = 15 - 4 = 11
Mary's age when she was 4 years less than 80% of Abi's age
= 4 p - 4
= 4 x 11 - 4
= 44 - 4
= 40
Answer(s): 40
