math
posted by wan on .
my age now is one third of mum's age.8years ago,i was a fifth of mum's age was at that time.how old will my mother be 8 years from now

Let my age now be A, and let Mum's age now be M. Then we know that:
A = M/3, so 3A = M
A8 = (M8)/5, so 5A40 = M8
but M = 3A, so 5A40 = 3A8
so 2A = 408 = 32
so A = 16
so M = 48.
Check it: A is onethird of M, and eight years ago I would have been 8 and Mum would have been 40.
But I want to know what Mum's age will be 8 years from now, so that will be 48 + 8 = 56.