Answer:
$180
Step-by-step explanation:
Since,
Commission = amount sales x commission %
Commission = 4,000 x 4.5%
Commission = $180
For this case we have the following expression:

From here, we must clear the value of a.
We then have the following steps:
Place the terms that depend on a on the same side of the equation:

Do common factor "a":

Clear the value of "a" by dividing the factor within the parenthesis:

Answer:
The clear expression for "a" is given by:

My answer is 38 students
( 22 students take one or both subjects)
P = 300/V
Because in order to isolate P, you have to divide V on both sides.