Let the two numbers be X and Y, X being the larger number if there is one. X+Y=230 X-Y=60 Take the second equation: X+Y=30 minus X on both sides Y=230-X Now solve by substitution: We know Y=230-X from the first problem, so replace Y in the second problem by (230-X) X-(230-X)=60 distribute the invisible -1 X-230+X=60 +230 on both sides 2X=290 divide by 2 on both sides X=145 Knowing this, we go back to the second equation to replace X with 145 and get Y: 145-Y=60 minus 145 on both sides -Y=-85 times -1 on both sides Y=85 X=145 Y=85