The perimeter of the triangle below is 4x + 3y. Find the measure
of the missing side.

Answer:
2x + 3y
Step-by-step explanation:
first you add the two known sides: (x-y)+(x+y) = 2x
Then you subtract the answer (2x) from the total perimiter (4x+3y) :
4x+3y-2x = (4x - 2x) + 3y = 2x + 3y