supplementary angles add up to 180°.
x = measure of such angle
x + 20 = measure of her sibling.
since "x" has 20 less than her sibling, then clearly her sibling has to have 20 more than "x".

Answer:
D
Step-by-step explanation:
Graph the points. Then count the units vertically and horizontally. See picture.
Three would be your answer :)
Take 0.5x4x3=6 So the answer is 6.