The interior angles of a triangle must add to 180 degrees.
110+5x+2x=180
110+7x=180
7x=70
x=10
Then plug in the x value into each angle expression
5(10)=50 degrees
2(10)=20 degrees
3.14
This is typically what you would use but there are several other numbers after 3.14
-8n+7=31
-8n+7-7=31-7
-8n=31-7
-8n=24
-8n÷(-8)=24÷(-8)
n=24÷(-8)
n=-24÷8
n=-3