Question

What is the value of y?



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y =

Answer 1

since this is an isosceles triangle

5x =40

divide by 5

x=8

the sum of all angles in a triangle is 180

5x+40 + 2y+20 = 180

substitute 40 in for 5x

40 + 40 + 2y+20 = 180

combine like terms

100 + 2y = 180

subtract 100 from each side

2y = 80

divide by 2

y= 40