Question

25.
Determine the value of x for which a || b if
m 3= 80 - X and m7 = 90 - 2x
90

10
30
70

Answer 1

Answer:

  x = 10

Step-by-step explanation:

Angles 3 and 7 are corresponding angles. They are congruent when lines 'a' and 'b' are parallel.

  ∠3 = ∠7

  80 -x = 90 -2x

  x = 10 . . . . . . . . . . . . add 2x-80 to both sides

_____

Check

When x=10, both angles 3 and 7 are 70°, so lines 'a' and 'b' are parallel.