PSLE
Jane baked some scones. She gave ¹₅ of the scones to her friends and 117 to her students. She was left with ⁷₂₀ of the scones. She packed these into 11 boxes. Some boxes contained 7 scones while the rest contained 9 scones.

1. How many scones were packed into the 11 boxes?
2. How many boxes contained 9 scones?

(a)
Fraction of the scones given to her students
= 1 - ¹₅ - ⁷₂₀

= 1 - ⁴₂₀ - ⁷₂₀
= ⁹₂₀

Number of scones that Jane gave to her students = 9 u

9 u = 117

1 u = 117 ÷ 9 = 13

Number of scones that were packed in 11 boxes
= 7 u
= 7 x 13
= 91

Number of scones that were packed in 11 boxes = 91

Boxes of 9	Scones	Boxes of 7	Scones	Total scones
11	99	0	0	99
10	90	1	7	97

If all the scones are packed in boxes of 9, the number of scones needed
= 11 x 9
= 99

Small difference
= 99 - 97
= 2

Big difference
= 99 - 91
= 8

Number of boxes of 7 scones 
= 8 ÷ 2
= 4

Number of boxes of 9 scones
= 11 - 4
= 7

Answer(s): (a) 91; (b) 7