Use the image to determine the height of the girl.

  72 in

Step-by-step explanation:

We know that 120 in is equal to the sum of the given height expressions.

  (9x) +(7x-8) = 120

  16x = 128 . . . . . . add 8 and simplify

  x = 8 . . . . . . . . . . divide by 16

  9x = girl's height = 9·8 = 72 . . . . inches

The height of the girl is 72 inches.

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.