Jim B. answered • 03/08/15
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Set up the system of equations, let the two numbers be x and y, and let x be the larger number:
x + y = 155 because their sum is 155
x - y = 15 because their difference is 15, and x is the larger number.
Solve for either variable, in either equation. I'd choose to solve for x in the second equation because it would keep all numbers positive:
x = 15 + y
If x = 15 + y, then substitute (15 + Y) in the first equation x + y = 155 and then solve for y.
Once you have y, solve for x knowing that x = 15 + y, then check your answers in both the original equations.
