For some value d, an isosceles triangle has at least one angle of 2d-40 degrees and at least one angle of d+20 degrees. What are all possible values of d?
Either
2(2d - 40) + (d + 20) = 180 simplify
4d - 80 + d + 20 = 180
5d - 60 = 180
5d = 240
d = 240/5 = 48°
Or
2(d + 20) + (2d - 40) = 180
2d + 40 + 2d - 40 = 180
4d = 180
d = 180/4 = 45°
