Examine △ABC shown below.
What is the measure of angle B?

Answer:
b = 57.6
Step-by-step explanation:
23 +3x +13 +2x=180
add the x's
5x
add the others
23+13=36
subtract 36 on both sides
36-36=0
180-36= 144
now get your 5x and divide by 5 on both sides
5/5 cancels out
144/5= 28.8
x= 28.8
now to find b
2·28.8= 57.6
to find 3x do the same
3 · 28.8 = 86.4
now double-check your answer by adding them all up and seeing if it = 180
57.6+86.4+36=180