Answer: x is equal to 4
Step-by-step explanation:
A triangle's angles sums up to 180°. So we already know that the three angles in this triangle add up to 180°. The equation would be as following.
(18x - 12) + 15x + (10x + 20) = 180
We first add like terms together.
43x + 8 = 180
We then substract 8 on both sides.
43x = 172
We finally divide 43 on both sides.
x = 4
