Answer:
a = 65
b = 73
c = 17
d = 138
Step-by-step explanation:
d + 42 = 180
c + d + 90 + 115 = 360
c + 138 + 205 = 360
c + 343 = 360
90 + b + c = 180
90 + b + 17 = 180
b + 107 = 180
a + b + 42 = 180
a + 73 + 42 = 180
a + 115 = 180
