The correct answer is x = 5
Triangle DBC is similar to triangle DBA.
So, by Similarity Theorem,
[tex]\begin{gathered} \frac{CB}{AB}=\frac{CD}{AD} \\ \\ \frac{21}{2x-5}=\frac{14}{10} \\ \text{Cross multiplying, we get} \\ 14(2x-5)=12\times10 \\ \text{Clearing the bracket, we get} \\ 28x-70=210 \\ \text{Collecting like terms, we get} \\ 28x=210\text{-70} \\ 28x\text{ = 140} \\ \text{Dividing both sides by 28, we get} \\ x=\frac{140}{28}=5 \\ x=5 \end{gathered}[/tex]
The correct answer is x = 5
