**Nan Hua SA 2 paper 2 question 14**

Betty saves some money to buy a bag. On the first day, she saved $6.50. On the second day, she saved $1.50 more than the first day. She continued saving $1.50 more than the previous day for another 4 days. Then she went to buy the bag and had $12 left. How much did the bag cost?