PSLE
Nora baked some puffs. She gave ¹₂ of the puffs to her friends and 147 to her students. She was left with ¹₅ of the puffs. She packed these into 11 boxes. Some boxes contained 7 puffs while the rest contained 10 puffs.

1. How many puffs were packed into the 11 boxes?
2. How many boxes contained 10 puffs?

(a)
Fraction of the puffs given to her students
= 1 - ¹₂ - ¹₅

= 1 - ⁵₁₀ - ²₁₀
= ³₁₀

Number of puffs that Nora gave to her students = 3 u

3 u = 147

1 u = 147 ÷ 3 = 49

Number of puffs that were packed in 11 boxes
= 2 u
= 2 x 49
= 98

Number of puffs that were packed in 11 boxes = 98

Boxes of 10	Puffs	Boxes of 7	Puffs	Total puffs
11	110	0	0	110
10	100	1	7	107

If all the puffs are packed in boxes of 10, the number of puffs needed
= 11 x 10
= 110

Small difference
= 110 - 107
= 3

Big difference
= 110 - 98
= 12

Number of boxes of 7 puffs 
= 12 ÷ 3
= 4

Number of boxes of 10 puffs
= 11 - 4
= 7

Answer(s): (a) 98; (b) 7