PSLE
Raeann baked some cookies. She gave ¹₁₀ of the cookies to her friends and 84 to her relatives. She was left with ¹₂ of the cookies. She packed these into 13 boxes. Some boxes contained 5 cookies while the rest contained 10 cookies.

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

(a)
Fraction of the cookies given to her relatives
= 1 - ¹₁₀ - ¹₂

= 1 - ¹₁₀ - ⁵₁₀
= ⁴₁₀

Number of cookies that Raeann gave to her relatives = 4 u

4 u = 84

1 u = 84 ÷ 4 = 21

Number of cookies that were packed in 13 boxes
= 5 u
= 5 x 21
= 105

Number of cookies that were packed in 13 boxes = 105

Boxes of 10	Cookies	Boxes of 5	Cookies	Total cookies
13	130	0	0	130
12	120	1	5	125

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

Small difference
= 130 - 125
= 5

Big difference
= 130 - 105
= 25

Number of boxes of 5 cookies 
= 25 ÷ 5
= 5

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

Answer(s): (a) 105; (b) 8