PSLE
Betty baked some cookies. She gave ¹₈ of the cookies to her friends and 114 to her relatives. She was left with ¹₂ of the cookies. She packed these into 18 boxes. Some boxes contained 6 cookies while the rest contained 10 cookies.

1. How many cookies were packed into the 18 boxes?
2. How many boxes contained 10 cookies?

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

= 1 - ¹₈ - ⁴₈
= ³₈

Number of cookies that Betty gave to her relatives = 3 u

3 u = 114

1 u = 114 ÷ 3 = 38

Number of cookies that were packed in 18 boxes
= 4 u
= 4 x 38
= 152

Number of cookies that were packed in 18 boxes = 152

Boxes of 10	Cookies	Boxes of 6	Cookies	Total cookies
18	180	0	0	180
17	170	1	6	176

If all the cookies are packed in boxes of 10, the number of cookies needed
= 18 x 10
= 180

Small difference
= 180 - 176
= 4

Big difference
= 180 - 152
= 28

Number of boxes of 6 cookies 
= 28 ÷ 4
= 7

Number of boxes of 10 cookies
= 18 - 7
= 11

Answer(s): (a) 152; (b) 11