Ai Tong School P5 Math CA1 2006 (Q40)

Tom and Joan have 125 books. Tom and Sammie have 305 books. If Sammie has 3 times as many books as Joan, how many books does Tom have?

Solution

Sam ----- 3 units
Joan ----- 1 unit


Tom + Joan (1 unit) ---- 125

Tom + Sammie (3 units) ----- 305


“Tom and Sammie” has more books than “Tom and Joan”
305 books – 125 books = 180 books.

The 180 extra books are due to the 2 extra units “Tom and Sammie” have, as compared to “Tom and Joan”. Therefore,

2 units ----- 180
1 unit ----- 180 divided by 2 = 90


Tom + Joan (1 unit) ---- 125

Tom + 90 ----- 125

Tom ----- 125 – 90 = 35

Answer: Tom has 35 books.