Question

the measure of angle W is 100 degrees, and the measure of angle Z is 68 degrees. what is the measure of angle Y

Answer 1

X +W = 180° = X + Y + Z

W = Y + Z

100° = Y +68°

32° = Y

Answer 2

W = Y + Z
100° = Y +68°
32° = Y . . . . . . . . . . . corresponds to the 2nd choice.

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X +W = 180° = X + Y + Z
so
W = Y + Z . . . . . knowing this little "shortcut" can simplify geometry problems