PSLE
Lynn and Bobby bought towels at the prices shown below.

3 Large towels for $10
4 Small towels for $5

1. Lynn bought an equal number of large and small towels. She spent $50 more on the large ones. How many towels did she buy altogether?
2. Bobby spent an equal amount of money on the large and small towels. What fraction of the towels he bought were large?

(a)
Number of large and small towels that Lynn bought is the same. Make the number of large and small towels the same. LCM of 3 and 4 is 12.

Cost of 3 large towels = $10
Cost of 12 large towels = 4 x 10 = $40

Cost of 4 small towels = $5
Cost of 12 small towels = 3 x 5 = $15

Difference in the cost of buying 12 small towels and 12 large towels
= 40 - 15
= $25

Number of sets of towels
= 50 ÷ 25
= 2

Number of towels that Lynn bought
= 2 x 2 x 12
= 48

(b)
Bobby spent an equal amount of money on the large and small towels.  Make the amount of money spent on the large and small towels the same.
LCM of 10 and 5 is 10.

Number of large towels that Bobby bought
= 3 x (10 ÷ 10)
= 3 x 1
= 3

Number of the small towels that Bobby bought
= 4 x (10 ÷ 5)
= 4 x 2
= 8

Fraction of the towels that Bobby bought that were large
= ³_{3 + 8}
= ³₁₁

Answer(s): (a) 48; (b) ³₁₁