A two digit number has a tens digit and a ones digit. Let's say x = tens digit and y = ones digit
"The sum of the digits is 5" x + y = 5
The next phrase is "the number multiplied by 3 is 42" but we need to represent the number using the digits. So they need to be multiplied first by their place value and added together. [Example: 34 = 3(10) + 4(1)]
The number is: 10x + y 3(10x + y) = 42
The system of equations: (two equations for two unknowns) x + y = 5 30x + 3y = 42
Then you can use substitution or elimination to combine and solve. I'll use elimination, multiply the entire top equation by -3 and add the equations together. y will cancel out
