Mark's auntie is 8 times as old as him. His auntie will be 32 years old in 8 years' time. In how many years' time will Mark's age be 75% that of his auntie's?
| |
Mark's auntie |
Mark |
Difference |
Before
(now) |
8x1 =
8 u |
1x1 =
1 u |
7x1 =
7 u |
| Change 1 |
+ 8 |
+ 8 |
|
| After 1 |
32 |
|
|
| Change 2 |
+ ? |
+ ? |
|
| After 2 |
4x7 =
28 u |
3x7 =
21 u |
1x7 =
7 u |
75% =
75100 =
34 Mark's auntie : Mark = 4 : 3
The difference in age between Mark's auntie and Mark always remains the same. Make the difference in age between Mark's auntie and Mark the same. LCM of 7 and 1 is 7.
8 u + 8 = 32
8 u = 32 - 8
8 u = 24
1 u = 24 ÷ 8 = 3
Number of years' time when Mark's age will be 75% that of his auntie's
= 28 u - 32
= 28 x 3 - 32
= 84 - 32
= 52
Answer(s): 52
