you could use this equation to help you solve it;
x + (x + 42) = 138
the first step is to combine like terms;
2x = 138 -42
2x = 96
X = 96/2
X = 48
we already solved for x now substitute it in the equation I gave you.
48 + (48 + 42) = 138
48 + 90 = 138
hope it helped...if you have any concerns just let me know:)
