Question

How do you find the x for this ?

Answer 1

The correct answer is 10 I just did this today

Answer 2

Answer: 10

So since all sides are congruent, all the angles should be equal as well. This means that if you divide 180 by 3 (number of angles) you should get 60. You then set the equation equal to 60 and solve:
2x^2-140=60
2x^2=200
x^2=100
x=10