Question

Find the value of x

Answer 1

The 3 angles in the triangle add up to 180 degrees.

So x + 74 + 73 + 37 + x = 180

2x = 180 - 74 - 73 - 37 = -4

x = -2 answer

3x = 2(x + 15)

x = 30 answer

Answer 2

The angles at the base are congruent, because the triangle is isosceles. The remaining angle is supplementary with 3x, so it is
`180-3x`

So, the sum of the three angles is

`(x+15)+(x+15)+(180-3x) = 210-x`

And the sum of the angles of a triangle is always 180:

`210-x = 180 \iff x = 210-180 = 30`