A friend bought 2 boxes of pencils and 8 notebooks for school and it cost him $11. He went back to the store the same day to buy school supplies for his younger brother. He spent $11.25 on 3 boxes of pencils and 5 notebooks. How much would notebooks cost?

Answer 1

2 p + 8 n = 11 ... multiply by 3/2 ... 3 p + 12 n = 16.50

3 p + 5 n = 11.25

subtracting equations (to eliminate p) ... 7 n = 5.25