Let [tex]a[/tex] be the first digit and [tex]b[/tex] the second. Then the number is [tex]x=10a+b[/tex]. The sum and difference of the two digits is 6, which means
[tex]\begin{cases}a+b=6\\a-b=6\end{cases}\implies a=6,b=0[/tex]
which means the number is [tex]x=6\times10+0=60[/tex]
