Answer:
7. x = 3
Explanation:
To find the value of x, use the triangle sum property. Every triangle has interior angles which add to 180 degrees. To solve, add the expressions and numbers together then set equal to 180. Then use inverse operations to solve for x.
7. 20x - 9 + 10x + 9 + 90 = 180 Subtract 90 from both sides.
20x - 9 + 10x + 9 = 90 Add -9 + 9 = 0
20x + 10x = 90 Add like terms 20x + 10x = 30x
30x = 90 Divide both sides by 30.
x = 3
Repeat this process for each problem.