Question

Given:

a||b, m∠2=3x+20
m∠7=2x−10

Find:
m∠3, m∠6

I'm confused. Please help!

Answer 1

<7 = <5 vertical angles

<5 = <3 alternate interior angles are equal when the lines are parallel

<2 +<3 = 180 straight line ( complementary angles)

3x+20 + <3 = 180

subtract 3x+20 from each side

<3 = 180 -(3x+20)

<3 = 180 -3x-20

<3 =160 -3x

but from above

<3 also = <5 = <7 and <7 = 2x-10

160 - 3x = 2x-10

add 3x to each side

160 = 5x-10

add 10 to each side

170 = 5x

x = 34

substitute in x=34 to find angle 3

<3 = 160 -3x

<3 =160 -3(34)

<3 =58

to find angle 6

<7+<6 = 180

<7 =<3 = 58

58 + <6 = 180

subtract 58 from each side

<6 = 180 -58

<6 = 122