Rosyth Sch 2007 PSLE Math Prelim Q46

The total cost of 28 textbooks and workbooks is $784.
3/4 of the books are textbooks and the remaining books are workbooks. A workbook cost half as much as a textbook. Find the difference in the price of a textbook and a workbook.

Solution

Workbook ----- 1 unit
Textbook ------ 2 units


3/4 of the books are textbooks ----- 3/4 x 28 = 21

Workbooks ----- 28 – 21 = 7

21 textbooks + 7 workbooks ---- $784

(21 x 2 units) + 7 units ----- $784

42 units + 7 units ----- $784

49 units ----- $784

1 unit ------ $784 divided 49 = $16

Answer: $16