30 points

what is the value of y?

enter your answer in the box.

y =

Step-by-step explanation:

Because of the Isosceles Triangle Theorem, angle B and angle C have the same measure.  If angle B is 75, then so is angle C.  By the Triangle Angle-Sum Theorem, all the angles of a triangle have to add up to equal 180 degrees.  That means that angle A = 180 - 75 - 75 which is 30 degrees.  Therefore,

Angle A = 30 degrees.   By the substitution property of equality,

4y + 10 = 30 and

4y = 20 so

y = 5

160

step-by-step explanation:

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i hope i