Solve each of the following equations for the indicated variable.

1. Solve for $d$: $I = \frac { 3 } { 4 }md+18$

   Hint (a):

   Start by subtracting $18$ from both sides.

2. Solve for $q$: $S = 25p + q$

   Answer (b):

   $q = S − 25p$

3. Solve for $n$: $PV = nRT$

• Hint (c):

  To solve for $n$ you will need to divide both sides by $RT$.