Question

Point E is drawn on the graph so that line EF is parallel to line CD.

On a coordinate plane, line C D goes through (negative 10, negative 2) and (10, 6). Point F is at (6, negative 4).

If the coordinates of point E are (, y), what is the value of y?

−8
−4
0
8

Answer 1

Slope of CD = (6 − (−2)) / (10 − (−10)) = 8 / 20 = 2/5.
EF must have the same slope. If E is at (−4, y) and F is (6, −4),

(y − (−4)) / (−4 − 6) = 2/5 → (y + 4) / (−10) = 2/5
y + 4 = −10*(2/5) = −4 → y = −8.

Answer: −8.