Question

What is the value of x​

Answer 1

90+(2x+10)+(5x+10)= 180
110+7x=180
7x=70
x=10

Answer 2

2x + 10 + 5x + 10 + 90 = 180 (add up all the angles and since it’s a triangle it must equal 180)
7x = 70 (add the like terms)
x = 10 (divide both sides by 7)