20r + 11r + –19r − –4 = –20

r = -2

Step-by-step explanation:

20r + 11r - 19r + 4 = -20

12r + 4 = -20

subtract 4 from both sides of the equation

12r + 4 - 4 = -20 - 4

12r = -24

divide both sides by 12

12r/12 = -24/12

r = -2

answer rather than having to add and subtract the measurements of the semi-circle, notice that the semicircle to the left of ad is actually identical in area to the blank semicircle-shaped space to the left of bc. so if we transferred the red semicircle into the blank space, we would end up with a square of side length 24 cm. the area of a square is s^2 = 24^2 = 676 cm^2.

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step-by-step explanation: