http://www.ck12.org Chapter 7. Similarity
The three lines are marked parallel, so you can set up a proportion.
a
20=
9
15
180 = 15 a
a= 12Example B
Findb.
To solve, set up a proportion.
12
9. 6
=
b
24
288 = 9. 6 b
b= 30Example C
Find the value ofxthat makes the lines parallel.