Question

The measure of angle w is 130 degrees. What is the measure of angle b? You can use the equations you just wrote to help. W=y. C+b=90. Y+c=180

Answer 1

b = 40

Explanation:

Solve system of equations.

1) w = y

2) c + b = 90

3) y + c = 180

Since we want to solve for b, second equation would be a good starting point.

c + b = 90

b = 90 - c

But what is c?

Let's make c the subject in 3rd equation.

y + c = 180

c = 180 - y

Insert c back in second equation.

b = 90 - c

b = 90 - (180 - y)

b = 90 - 180 + y

b = -90 + y

All we need now is y. Notice that in the first equation w equals y and w is 130°, which means y is also 130°. Substitute again.

b = -90 + y

b = -90 + w

b = -90 + 130

b = 40

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This is how it looks like if you solve it in one go (same procedure as above but in one place).

c + b = 90

b = 90 - c

b = 90 - (180 - y)

b = -90 + y

b = -90 + w

b = -90 + 130

b = 40