Question 1207157
t, for tens place
u, for units or ones place
{{{10t+u}}}


Description:
{{{system(t+u=12,10u+t=15+2(10t+u))}}}



{{{10u+t=15+2*10t+2*u}}}

{{{10u+t=15+20t+2u}}}

{{{8u=15+19t}}}

{{{8(12-t)=15+19t}}}   (substitution using digit sum equation)

{{{96-8t=15+19t}}}

{{{96-15=19t+8t}}}

{{{81=27t}}}

{{{t=3}}}------------{{{u=9}}}