Question

In the two digit number x,both the sum and the difference of its digit is 6. What is the value of x ?

Answer 1

Let
`a` be the first digit and
`b` the second. Then the number is
`x=10a+b`. The sum and difference of the two digits is 6, which means


`\begin{cases}a+b=6\\a-b=6\end{cases}\implies a=6,b=0`

which means the number is
`x=6*10+0=60`