Question 163114
Let's let the first digit be A and the second digit be B. 
The number can be represented as,
{{{10*A+B}}}
You also know that 
1.{{{B=3A}}}
When you interchange the digits, the new number becomes, 
{{{10*B+A}}}
And then you also know that
2.{{{(10*A+B)+(10*B+A)=88}}}
2.{{{11A+11B=88}}}
2.{{{A+B=8}}}
Plug the value for B from eq. 1 into eq. 2 and solve for A.
2.{{{A+3A=8}}}
{{{4A=8}}}
{{{A=2}}}
From eq. 1,
{{{B=3(2)=6}}}
The original number is 26, the interchange number is 62.
As a check, add them together to get 88.
.
.
.
A=2
B=6