since the bottom and top lines are congruent they are 'interior angles on the same side of a transversal' which are always supplementary, so that's where 180 comes from.
calculate the equation and you'll get x=21 :D
next to find 1 just put 21 in place of x: 3(21)-3=60
since it's supplementary to angle 1 you take 180-60=120
