Question 898623
let x be the angle, then we are given
3x - 60 = 180 -x
add x to both sides of =
4x - 60 = 180
add 60 to both sides of =
4x = 240
x = 60
check our answer
3*60 - 60 = 180 -60
180 - 60 = 120
120 = 120
our answer, the angle is 60 degrees, checks  :-)