please show work so i know how to do it :)))

70

Step-by-step explanation:

the red lines mean the two sides are equal

so its an isosceles triangle meaning the two angles other than the 40° one are equal

the inner angles of a triangle must add up to 180

so 180-40 = 2x

140 = 2x

x = 140/2 = 70

x=70

Step-by-step explanation:

let unknown angle be a

then,a=x(base angle of an isosceles triangle)

a+x+40=180

x+x=180-40(a=x)

2x=140

x=70

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step-by-step explanation:

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