PSLE
Anna baked some shortbreads. She gave ¹₆ of the shortbreads to her students and 80 to her colleagues. She was left with ¹₂ of the shortbreads. She packed these into 13 boxes. Some boxes contained 8 shortbreads while the rest contained 10 shortbreads.

1. How many shortbreads were packed into the 13 boxes?
2. How many boxes contained 10 shortbreads?

(a)
Fraction of the shortbreads given to her colleagues
= 1 - ¹₆ - ¹₂

= 1 - ¹₆ - ³₆
= ²₆

Number of shortbreads that Anna gave to her colleagues = 2 u

2 u = 80

1 u = 80 ÷ 2 = 40

Number of shortbreads that were packed in 13 boxes
= 3 u
= 3 x 40
= 120

Number of shortbreads that were packed in 13 boxes = 120

Boxes of 10	Shortbreads	Boxes of 8	Shortbreads	Total shortbreads
13	130	0	0	130
12	120	1	8	128

If all the shortbreads are packed in boxes of 10, the number of shortbreads needed
= 13 x 10
= 130

Small difference
= 130 - 128
= 2

Big difference
= 130 - 120
= 10

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

Number of boxes of 10 shortbreads
= 13 - 5
= 8

Answer(s): (a) 120; (b) 8