These two angles equal a line when added together. A line equals 180°. Add angle (2x+10) and angle (x+5) and set equal to 180 and solve for x.
(2x + 10) + (x + 5)= 180
combine like terms
3x + 15= 180
subtract 15 from both sides
3x= 165
divide both sides by 3
x= 55
Hope this helps! :)
