An office supply company orders packs of pens for two of its stores. for the first store, the order is for 60 packs of ballpoint pens and 25 packs of gel pens, for a total of $355. for the second store, the order is for 120 packs of ballpoint pens and 30 packs of gel pens, for a total of $570. create and solve a system of equations to determine the cost of one pack of ballpoint pens and one pack of gel pens. a. the cost of one pack of ballpoint pens is $3 and the cost of one pack of gel pens is $7. b. the cost of one pack of ballpoint pens is $7 and the cost of one pack of gel pens is $3. c. the cost of one pack of ballpoint pens is $3 and the cost of one pack of gel pens is $4. d. the cost of one pack of ballpoint pens is $4 and the cost of one pack of gel pens is $3.