PSLE
Jade and Mark bought mangoes at the prices shown below.

4 Large mangoes for $15
7 Small mangoes for $9

1. Jade bought an equal number of large and small mangoes. She spent $207 more on the large ones. How many mangoes did she buy altogether?
2. Mark spent an equal amount of money on the large and small mangoes. What fraction of the mangoes he bought were large?

(a)
Number of large and small mangoes that Jade bought is the same. Make the number of large and small mangoes the same. LCM of 4 and 7 is 28.

Cost of 4 large mangoes = $15
Cost of 28 large mangoes = 7 x 15 = $105

Cost of 7 small mangoes = $9
Cost of 28 small mangoes = 4 x 9 = $36

Difference in the cost of buying 28 small mangoes and 28 large mangoes
= 105 - 36
= $69

Number of sets of mangoes
= 207 ÷ 69
= 3

Number of mangoes that Jade bought
= 3 x 2 x 28
= 168

(b)
Mark spent an equal amount of money on the large and small mangoes.  Make the amount of money spent on the large and small mangoes the same.
LCM of 15 and 9 is 45.

Number of large mangoes that Mark bought
= 4 x (45 ÷ 15)
= 4 x 3
= 12

Number of the small mangoes that Mark bought
= 7 x (45 ÷ 9)
= 7 x 5
= 35

Fraction of the mangoes that Mark bought that were large
= ¹²_{12 + 35}
= ¹²₄₇

Answer(s): (a) 168; (b) ¹²₄₇