PSLE
Yen baked some cookies. She gave ¹₈ of the cookies to her students and 87 to her colleagues. She was left with ¹₂ of the cookies. She packed these into 11 boxes. Some boxes contained 8 cookies while the rest contained 12 cookies.

1. How many cookies were packed into the 11 boxes?
2. How many boxes contained 12 cookies?

(a)
Fraction of the cookies given to her colleagues
= 1 - ¹₈ - ¹₂

= 1 - ¹₈ - ⁴₈
= ³₈

Number of cookies that Yen gave to her colleagues = 3 u

3 u = 87

1 u = 87 ÷ 3 = 29

Number of cookies that were packed in 11 boxes
= 4 u
= 4 x 29
= 116

Number of cookies that were packed in 11 boxes = 116

Boxes of 12	Cookies	Boxes of 8	Cookies	Total cookies
11	132	0	0	132
10	120	1	8	128

If all the cookies are packed in boxes of 12, the number of cookies needed
= 11 x 12
= 132

Small difference
= 132 - 128
= 4

Big difference
= 132 - 116
= 16

Number of boxes of 8 cookies 
= 16 ÷ 4
= 4

Number of boxes of 12 cookies
= 11 - 4
= 7

Answer(s): (a) 116; (b) 7