Question 345473
Let A = A's present age
Let B = B's present age
;
In a years, A will be n times as old as B then; 
A + a = n(B + a)
A + a = nB + na
A = nB + na - a; is A's present age


and b years ago, A was m times as old as B. 
A - b = m(B - b)
Find B
m(B - b) = A - b
B - b = {{{((A - b))/m}}}
B = {{{((A - b))/m}}} + b; is B's present age


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