Find the value of x. the diagram is not to scale.

a. x=70
b. none of these
c. x=20
d. x=16

For this case, the first thing to do is to observe that we are in the presence of an isosceles triangle.
 We then have two equal sides:
 RS = ST
 Thus,
 Angle R = Angle T
 Then, we have the following equation:
 5x = 180- (5x-20)
 From here, we clear the value of x:
 5x = -5x + 180 + 20
 10x = 200
 x = 200/10
 x = 20
 
 the value of x is: 
 C. x = 20

Letter c i’d say