<PRE><B>Question 739768</B>
we are given the parallelogram ABDC which means that AB is parallel to DC, furthermore opposite angles are equal which means

Angle A is equal to angle C and angle D is equal to angle B, also angles A and D add up to 180 degrees (supplementary angles) as well as angles B and C.  So we have the following equations.

3x+10+5y=180
8x+5+angle C =180

but angle C = angle A so
8x+5+3x+10=180
11x+15=180
11x=165
x=15

substituting for x in equation one, we have

3*15 + 10 + 5y = 180
55 + 5y = 180
5y = 125
y = 25

so x = 15 and y = 25

that means angle A = 3 * 15 + 10 = 55, angel B = 8 * 15 + 5 = 125
angle D = 5 * 25 = 125 and angle C = angle A =55
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