Ada yang bisa no 2 ???

140-15 / b-15 = 100-0 / 40-0
125 / b-15 = 100 / 40
125 / b-15 = 5 / 2
250 = 5b-75
250+75 = 5b
325 = 5b
b = 325 / 5
b = 65°B ( B )

Semoga membantu...^^