1ab + 36 = ab1
=> 100 + 10a + b + 36 = 100a + 10b + 1
=> 100a - 10a + 10b - b = 100 + 36 - 1
=> 90a + 9b = 135
=> 9 ( 10a + b ) = 135
=> 10a + b = 15
=> a = 1 ; b = 5
\(\overline{1ab}+36=\overline{ab1}\)
\(\Rightarrow100+\overline{ab}+36=\overline{ab}.10+1\)
\(\Rightarrow\overline{ab}.10-\overline{ab}=100+36-1\)
\(\Rightarrow9.\overline{ab}=135\Rightarrow\overline{ab}=15\)