Question 1077364
a=tens
b=ones 

{{{system(a+b=7,a=2b+1)}}} Substitute 2b+1 for a,

{{{(2b+1)+b=7}}}

{{{2b+1+b=7}}}

{{{3b+1=7}}}

{{{3b=6}}}

{{{highlight(b=2)}}} 2*2=4+1=5 {{{highlight(a=5)}}} 

{{{highlight(Number:52)}}}