Answer:
x = 27
Explanation:
BR is parallel to QC therefore ΔBDR and ΔQDC are similar.
The sides are in proportion:
![(BD)/(QD)=(RD)/(CD)](https://img.qammunity.org/2020/formulas/mathematics/high-school/w660u9sbnf6wqgxfgfzpg23mlxf0e134um.png)
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
![\boxed{x=27}](https://img.qammunity.org/2020/formulas/mathematics/high-school/wj9ew94ocoyzannjjtf7496x3y64oy02qx.png)