Answer:
x = 27
Explanation:
BR is parallel to QC therefore ΔBDR and ΔQDC are similar.
The sides are in proportion:

We have
BD = 26 + 39 = 65
QD = 39
RD = 18 + x
CD = x
Substitute:
cross multiply
use distributive property
subtract 39x from both sides
divide both sides by 26
