PSLE
Barbara baked some muffins. She gave ¹₈ of the muffins to her friends and 84 to her relatives. She was left with ¹₂ of the muffins. She packed these into 18 boxes. Some boxes contained 5 muffins while the rest contained 7 muffins.

1. How many muffins were packed into the 18 boxes?
2. How many boxes contained 7 muffins?

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

= 1 - ¹₈ - ⁴₈
= ³₈

Number of muffins that Barbara gave to her relatives = 3 u

3 u = 84

1 u = 84 ÷ 3 = 28

Number of muffins that were packed in 18 boxes
= 4 u
= 4 x 28
= 112

Number of muffins that were packed in 18 boxes = 112

Boxes of 7	Muffins	Boxes of 5	Muffins	Total muffins
18	126	0	0	126
17	119	1	5	124

If all the muffins are packed in boxes of 7, the number of muffins needed
= 18 x 7
= 126

Small difference
= 126 - 124
= 2

Big difference
= 126 - 112
= 14

Number of boxes of 5 muffins 
= 14 ÷ 2
= 7

Number of boxes of 7 muffins
= 18 - 7
= 11

Answer(s): (a) 112; (b) 11