Gabby will be 63 years old in 7 years' time. Now, Mary's age is 34 of Gabby's age. What was Mary's age when she was 6 years less than 90% of Gabby's age?
| |
Mary |
Gabby |
Difference |
| Before |
9 p - 6 |
10 p |
1 p + 6 |
| Change 1 |
+ ? |
+ ? |
|
| After 1 (Now) |
3 u |
4 u |
1 u |
| Change 2 |
+ 7 |
+ 7 |
|
| After |
3 u + 7 |
63 |
|
Gabby's age in 7 years' time = 4 u + 7
4 u + 7 = 63
4 u = 63 - 7
4 u = 56
1 u = 56 ÷ 4 = 14
Difference between Gabby's age and Mary's age
= 1 u
= 14
90% =
90100 =
910 Difference in Gabby's age and Mary's age at first
= 10 p - (9 p - 6)
= 1 p + 6
The difference in age between Gabby and Mary remains unchanged.
1 p + 6 = 14
1 p = 14 - 6 = 8
Mary's age when she was 6 years less than 90% of Gabby's age
= 9 p - 6
= 9 x 8 - 6
= 72 - 6
= 66
Answer(s): 66
