PSLE
Jaslyn baked some biscuits. She gave ²₅ of the biscuits to her relatives and 140 to her friends. She was left with ¹₄ of the biscuits. She packed these into 16 boxes. Some boxes contained 4 biscuits while the rest contained 8 biscuits.

1. How many biscuits were packed into the 16 boxes?
2. How many boxes contained 8 biscuits?

(a)
Fraction of the biscuits given to her friends
= 1 - ²₅ - ¹₄

= 1 - ⁸₂₀ - ⁵₂₀
= ⁷₂₀

Number of biscuits that Jaslyn gave to her friends = 7 u

7 u = 140

1 u = 140 ÷ 7 = 20

Number of biscuits that were packed in 16 boxes
= 5 u
= 5 x 20
= 100

Number of biscuits that were packed in 16 boxes = 100

Boxes of 8	Biscuits	Boxes of 4	Biscuits	Total biscuits
16	128	0	0	128
15	120	1	4	124

If all the biscuits are packed in boxes of 8, the number of biscuits needed
= 16 x 8
= 128

Small difference
= 128 - 124
= 4

Big difference
= 128 - 100
= 28

Number of boxes of 4 biscuits 
= 28 ÷ 4
= 7

Number of boxes of 8 biscuits
= 16 - 7
= 9

Answer(s): (a) 100; (b) 9