Question

Which equation can be used to solve for x in the following diagram

Answer 1

equation C would be your answer.

(3x + 12) and x represent 180 combined.

so (3x + 12) + x = 180, combine your like terms which is your x, x + 3x = 4x

4x + 12 = 180 (subtract 12 on both sides)
-12 -12
————————
4x = 168 (divide 4 on both sides)
—- ——
4 4

x = 42

to check your answer you replace the x with 42 and you should get 180 as your answer

(3x+12) = 180
3(42)+12 = 180
126 + 12 = 138

x = 42

138 + 42 = 180

Answer 2

C. (3x + 12) + x = 180

Explanation:

`(3x + 12) \degree + x \degree = 180 \degree \\ \{angles \: on \: straight \: line \}`

group like terms together:

`(3x + x) + 12 = 180 \\ 4x = 180 - 12 \\ 4x = 168 \\ x = 42`