Question

In triangle ABC, If angle A + Angle B = 65 degree, angle B + angle C = 140 degree, then find the value of angle B.

Answer 1

a+b=65,b+c=140
a+b+c=180
65+c=180
c=115
b+c=140
b=140-115=25

Answer 2

in triangle ABC,

∠C= 180°-(<A +<B)

∠C=180°-65°

∠C=115°

∠B=140°-115°=25°

∠B=25°