the perimeter of MATH is 4w + 6 and the perimeter of GEOM is 6w - 8. the perimeters are the same so set them equal,
4w + 6 = 6w - 8... use inverse to get all like terms on opposite sides
-4w + 8 = -4w + 8
14 = 2w... divide both side by 2 to get w alone
÷2 = ÷2
7 = w
so B. 7 is the answer