we know two supplementary angles add up to be 180°.we can create our first equaition, using
smaller angle + larger angle = 180 s + l = 180
we can create our second equation using two times the smaller = larger 2s = l our two equations are: 2s = l s + l = 180
now that we have the two equations, we can solve using subsitution to isolate the variable. s + l = 180 s + (2s) = 180 simpify.
3s = 180 s = 60
the smaller angle has a value of 60. now, remember that the larger angle is two times the smaller.
60 x 2 = 120
smaller angle: 60 larger angle: 120 we know this is correct because we know the smaller is 1/2 or 1:2 or 2:4 times the bigger, and the two angles add up to be 180 (60 + 120)