Question

Find B if A=70° and a + b = 80°

Answer 1

Answer:

B=30°

Step-by-step explanation:

Recall that the sum of interior angles of a triangle equals to 180°. So basically

$A+B+\alpha+\beta=180^{\circ}$

$\implies B + {70}^{ \circ} + {80}^{ \circ} = {180}^{ \circ} \\ \implies B = {180}^{ \circ} - {150}^{ \circ} \\ \implies B = \boxed{{30}^{ \circ} }$