PSLE
Fanny baked some cupcakes. She gave ¹₁₀ of the cupcakes to her relatives and 88 to her friends. She was left with ¹₂ of the cupcakes. She packed these into 18 boxes. Some boxes contained 5 cupcakes while the rest contained 7 cupcakes.

1. How many cupcakes were packed into the 18 boxes?
2. How many boxes contained 7 cupcakes?

(a)
Fraction of the cupcakes given to her friends
= 1 - ¹₁₀ - ¹₂

= 1 - ¹₁₀ - ⁵₁₀
= ⁴₁₀

Number of cupcakes that Fanny gave to her friends = 4 u

4 u = 88

1 u = 88 ÷ 4 = 22

Number of cupcakes that were packed in 18 boxes
= 5 u
= 5 x 22
= 110

Number of cupcakes that were packed in 18 boxes = 110

Boxes of 7	Cupcakes	Boxes of 5	Cupcakes	Total cupcakes
18	126	0	0	126
17	119	1	5	124

If all the cupcakes are packed in boxes of 7, the number of cupcakes needed
= 18 x 7
= 126

Small difference
= 126 - 124
= 2

Big difference
= 126 - 110
= 16

Number of boxes of 5 cupcakes 
= 16 ÷ 2
= 8

Number of boxes of 7 cupcakes
= 18 - 8
= 10

Answer(s): (a) 110; (b) 10