Answer:
The answer to your question is: 21
Step-by-step explanation:
Data
AB = BC = CD
BQ = 21
QD = ?
PC = 11
Process
Here there are 2 triangles
ΔQCB and ΔQCD
These triangles share one side QC
And one side measures the same BC = CD
And the ∠ BCQ = ∠ DCQ
Then these triangles are congruents SAS
if QB = 21 then QD = 21
