algebra
posted by Anonymous .
An office supply store sells pens for $3 and notebooks for $5. Before school started, the store sold 12 more pens than notebooks and made $324. Which system of equations could be used to find the number of pens, p, and notebook, n that the store sold that day?

P = N + 12
5N + 3P = 324
Substitute N+12 for P in second equation and solve for N. Insert that value into the first equation and solve for P. Check by inserting both values into the second equation.