P left triangle = (2x+8) + (2x+7) + 2x
combine like terms
P left =6x+15
P right triangle = 2x+ 2x+ (3x+7)
combine like terms
7x+7
since the perimeters of the triangles are equal, set them equal
6x+15 = 7x+7
subtract 6x from each side
15 =x+7
subtract 7 from each side
8 =x
AB = 2x+8 = 2*8 +8 = 16+8 = 24
BC =2x+7 = 2*8+7 = 16+7 = 23
CA = 2x =2*8 = 16
PQ = 2x = 16
QR = 2x = 16
PR = 3x+7 = 3*8+7 = 24+7 = 31