Answer:
Explanation:
1) phone
38.95 = 0.03 * mins + 29.95
9.00 = 0.03 * mins
9.00 /0.03 = mins
300 = mins
so he used 300 minutes :)
2) books
8.70 =14 * bookPrice + 2.40
6.30 = 14 * bookPrice
6.30 / 14 = bookPrice
0.45 = bookPrice
each book cost 45 cents :)