When 9 is subtracted from the product

5

Given, 9 is subtracted from the product of $p$ and $4 .$

Then, $4 p-9=11$

$\Rightarrow \quad 4 p=11+9 \quad$ [transposing $-9$ to RHS]

$\Rightarrow \quad 4 p=20$

$\Rightarrow \quad \quad \frac{4 p}{4}=\frac{20}{4} \quad \quad$ [dividing both sides by 4$]$

$\therefore \quad p=5$

Hence, the value of $p$ is 5 .