Answer:
x= 60
Explanation:
We need to find the last inside angle first. Supplementary angles will add up to 180°. 180° - 120° = 60°.
We also know that all of the inside angles of a triangle will add up to 180°.
180° = 60 + (x+5) + (x-5)
Let's get rid of the parentheses to see it easier:
180° = 60 + x + 5 + x - 5
Combine like terms on the right side:
180° = 60 + 2x (the fives canceled each other out)
Subtract 60 from both sides to get the term with x alone:
120° = 2x
Divide both sides by 2 to get x alone:
60° = x
Now check by filling in 60 for x in our equation where all angles add up to 180°.
180° = 60 + (60+5) + (60-5)
180° = 60 + 65 + 55
180° = 60 + 120
180° = 180°
It's right!