this is an isoscele triangle, AB = BC, and the angle A is equal angle C.
8y - 7 = 73
8y = 73 + 7
8y = 80
y = 80 : 8
y = 10
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the sum of the interior angles is 180°
180 - 73 - 73 = 34° (angle B)
6x + 4 = 34
6x = 30
x = 30 : 6 =
x = 5