Question

Find the value of x. How do you know your answer is correct.

Answer 1

3x - 20 + 2x = 180 because the angle on a straight line is 180 degrees

5x = 200

x = 40

Answer 2

Answer: x = 32

Step-by-step explanation:

(3x - 20°) and 2x° form a linear pair (because they are adjacent and on a straight angle). Linear Pairs are supplementary which means their sum is 180°

3x - 20 + 2x = 180     Sum of supplementary angles equal 180°

         5x - 20 = 180   Simplify (added like terms of 3x and 2x)

                 5x = 200  Addition Property of Equality

                   x = 40     Division Property of Equality

Check:

3x - 20 = 3(40) - 20   = 120 - 20   = 100    ---> ∠(3x - 20) = 100

2x = 2(40)   = 80   ---------------------------------------->    ∠(2x) =  80

                                                                   sum of angles = 180