Question 679031
{{{A = 11B}}}
{{{A + n = 5(B+n)}}}
{{{A + n + 5 = 3(B + n + 5)}}}

In the last 2 equations replace A with 11B (first equation) and distribute on the right side of the equations:

{{{11B + n = 5B + 5n}}}
{{{11B + n + 5 = 3B + 3n +15}}}

Bring the right side B-terms in the left side and the n's and 5 from the left side to the right side:

{{{6B = 4n}}}
{{{8B = 2n + 10}}}

Divide by 2 the first equation:

{{{3B = 2n}}}
{{{8B = 2n + 10}}}

Subtract first equation from the second one:

{{{5B = 10}}}

{{{B = 2}}}

{{{A = 11B = 22}}}

In {{{n=3}}} years {{{A=25}}} and {{{B=5}}} (A five times older than B), and five years after that {{{A = 30}}} and {{{B=10}}} (A three times older than B).