Solve the Problem $s$ , Minus Its Cost $c$ If a New Printer Costs

Solve the problem.
-The markup on an item is its selling price, $s$ , minus its cost, $c$ . If a new printer costs $\$ 284.25$ and it sells for $\$ 399.99$ , what is the markup?

A) $\$ 115.74$
B) $\$ 684.24$
C) $\$ 124.26$
D) $\$ 115$