soalnya yang b,c,d aja

b. 180 = 40 + 34 + 2x
180 = 74 + 2x
180 - 74 = 2x
106 = 2x
53 = x

c. 180 = 30 + 2x + 60
180 = 90 + 2x
180 - 90 = 2x
90 = 2x
45 = x

d. (sudut siku2)
90 = 3x + 2x + x
90 = 6x
90/6 = x
15 = x