PSLE
Lucy baked some cupcakes. She gave ¹₂ of the cupcakes to her students and 60 to her colleagues. She was left with ⁷₂₀ of the cupcakes. She packed these into 15 boxes. Some boxes contained 8 cupcakes while the rest contained 10 cupcakes.

1. How many cupcakes were packed into the 15 boxes?
2. How many boxes contained 10 cupcakes?

(a)
Fraction of the cupcakes given to her colleagues
= 1 - ¹₂ - ⁷₂₀

= 1 - ¹⁰₂₀ - ⁷₂₀
= ³₂₀

Number of cupcakes that Lucy gave to her colleagues = 3 u

3 u = 60

1 u = 60 ÷ 3 = 20

Number of cupcakes that were packed in 15 boxes
= 7 u
= 7 x 20
= 140

Number of cupcakes that were packed in 15 boxes = 140

Boxes of 10	Cupcakes	Boxes of 8	Cupcakes	Total cupcakes
15	150	0	0	150
14	140	1	8	148

If all the cupcakes are packed in boxes of 10, the number of cupcakes needed
= 15 x 10
= 150

Small difference
= 150 - 148
= 2

Big difference
= 150 - 140
= 10

Number of boxes of 8 cupcakes 
= 10 ÷ 2
= 5

Number of boxes of 10 cupcakes
= 15 - 5
= 10

Answer(s): (a) 140; (b) 10