In order to answer the question, we are going to use the property that tells us that the sum of the internal angles of a triangle should give 180 degrees:
so in our case, angle A + angle B + angle C = 180
that is:
(5 x + 8 ) + (4 x + 8) + 74 = 180
combining like terms on the left:
9 x +16 + 74 = 180
9 x + 90 = 180
subtracting 90 from both sides:
9 x = 90
dividing by 9:
x = 90/9 = 10
So x is 10 degrees, therfore :
A = 5 x + 8 = 5 (10) + 8 = 58 degrees
