Tao Nan School P5 SA2 2007 Math Q37

A book and 3 pens cost $11.25. The book cost twice as much as a pen. Find the cost of 4 books.

Solution

Book ----- 2 units
Pen ----- 1 unit

1 book + 3 pens ----- $11.25
2 units + 3 units ----- $11.25
5 units ----- $11.25
1 unit ----- $11.25 divided by 5 = $2.25

(4 books) 4 x 2 units ---- 8 units
8 units ----- 8 x $2.25 = $18

Answer: The cost of 4 books is $18.