PSLE
Jean and Daniel bought storybooks at the prices shown below.

3 Large storybooks for $10
5 Small storybooks for $6

1. Jean bought an equal number of large and small storybooks. She spent $128 more on the large ones. How many storybooks did she buy altogether?
2. Daniel spent an equal amount of money on the large and small storybooks. What fraction of the storybooks he bought were large?

(a)
Number of large and small storybooks that Jean bought is the same. Make the number of large and small storybooks the same. LCM of 3 and 5 is 15.

Cost of 3 large storybooks = $10
Cost of 15 large storybooks = 5 x 10 = $50

Cost of 5 small storybooks = $6
Cost of 15 small storybooks = 3 x 6 = $18

Difference in the cost of buying 15 small storybooks and 15 large storybooks
= 50 - 18
= $32

Number of sets of storybooks
= 128 ÷ 32
= 4

Number of storybooks that Jean bought
= 4 x 2 x 15
= 120

(b)
Daniel spent an equal amount of money on the large and small storybooks.  Make the amount of money spent on the large and small storybooks the same.
LCM of 10 and 6 is 30.

Number of large storybooks that Daniel bought
= 3 x (30 ÷ 10)
= 3 x 3
= 9

Number of the small storybooks that Daniel bought
= 5 x (30 ÷ 6)
= 5 x 5
= 25

Fraction of the storybooks that Daniel bought that were large
= ⁹_{9 + 25}
= ⁹₃₄

Answer(s): (a) 120; (b) ⁹₃₄