Adam's age is a multiple of 8 this year.
His age 5 years ago was a multiple of 9.
Adam's age is between 30 and 40.
- In how many years' time will Adam's age be a multiple of 5?
- How many years ago was Adam's age a multiple of 9?
(a)
Multiple of 8: 8, 16, 24, 32
Multiple of 8 (-5): 3, 11, 19, 27
Multiples of 9: 9, 18, 27
Adam's age this year = 32
Multiples of 5: 5, 10, 15, 20, 25, 30, 35
Number of years' time when Adam will be a multiple of 5
= 35 - 32
= 3
(b)
Multiples of 9: 9, 18, 27
Least number of years ago when Adam's age was a multiple of 9
= 32 - 27
= 5
Answer(s): (a) 3; (b) 5