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 7?
- How many years ago was Adam's age a multiple of 10?
(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 7: 7, 14, 21, 28, 35
Number of years' time when Adam will be a multiple of 7
= 35 - 32
= 3
(b)
Multiples of 10: 10, 20, 30
Least number of years ago when Adam's age was a multiple of 10
= 32 - 30
= 2
Answer(s): (a) 3; (b) 2