Question

lines l and m are parallel. Measure def is three times abc. Measure bcd=25%, measure cde=55%. Find measure abc.

Answer 1

<ABC= 45 degrees

Angles on a straight line add up to 180

3x+ x= 180

4x=180

x=180÷4

x=45

Answer 2

Measure of ABC = 15 degrees.

Explanation:

We draw 2 lines parallel to l and m , one passing through pont C ( n) and the other passing through point D (p).

If < abc = x degrees then the angle below line n = 25 - x. As the one above = x degrees ( alternate to < ABC).

The angle below line p = < DEF 3x degrees (alternate angles)

So as < CDE = 55:

25 - x + 3x = 55

2x = 30

x = 15.

So < ABC = 15 degrees.