Question 1199026
m Mother
c Son


Description becomes system:
{{{system(m-4=4(c-4),m+c=56-8)}}}


The question means, find m when c is 0.
{{{m=48-c}}}

{{{m=48-0}}}

{{{m=48}}} {{{when}}} {{{c=0}}}
Mother was 48 y.o.  when son was born.