In convex pentagon $ABCDE$, angles $A$, $B$ and $C$ are congruent and angles $D$ and $E$ are congruent. If the measure of angle $A$ is 40 degrees less than the measure of angle $D$, what is the measure of angle $D$?
+128475 The interior angles of a pentagon will sum to 540°
So we have that
A = D - 40
B = D - 40
C = D - 40
E = D
So we have that
A + B + C + D + E = 540 and substituting, we have
D - 40 + D - 40 + D - 40 + D + D = 540 simplify
5D - 120 = 540 add 120 to both sides
5D = 660 divide both sides by 5
D = 132°
