Question 330504
I assume this question has two parts.

We given a formula and what the letters represent in the formula.

For part (a), we are solving for F.

F = n/15

F = 41670/15

F = 2778 equivalent students

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For part (b), we are solving for n.  This means we need to isolate n on one side of the equation.

F = n/15

Multiply both sides of the equation by 15/1 to clear the fraction on the right side.  

F * 15/1 = n/15 * 15/1

15F = n

Did you follow?