Ryan,
We quite often use one letter to stand for a variable, as in your equation. When we do then by placing two letters adjacent to each other we mean to multiply the values. Thus, for example your equation
I = PRT
means
I = P R T
Thus, with I = $2,880, R = 0.08 and P = $12,000 the equation becomes
$2,880 = $12,000 0.08 T
or
$2,880 = $960 T
Thus
T = ^{$2,880}/_{$960} = 3
Penny
