Question 264377
The units digit, u
The tens digit, t


{{{system(t=u-2,t+u=12)}}}


substituting for t,
{{{(u-2)+u=12}}}
{{{2u-2=12}}}
{{{u-1=6}}}
{{{u=7}}}
and then
{{{t=5}}}


The number is 57.