Adam's age is a multiple of 9 this year.
His age 8 years ago was a multiple of 7.
Adam's age is between 30 and 40.
- In how many years' time will Adam's age be a multiple of 8?
- How many years ago was Adam's age a multiple of 7?
(a)
Multiple of 9: 9, 18, 27, 36
Multiple of 9 (-8): 1, 10, 19, 28
Multiples of 7: 7, 14, 21, 28
Adam's age this year = 36
Multiples of 8: 8, 16, 24, 32, 40
Number of years' time when Adam will be a multiple of 8
= 40 - 36
= 4
(b)
Multiples of 7: 7, 14, 21, 28, 35
Least number of years ago when Adam's age was a multiple of 7
= 36 - 35
= 1
Answer(s): (a) 4; (b) 1