PSLE
Three boys, Kai, Nat and Don had the same number of notes. Kai and Nat each had of mix of $20-notes and $2-notes. Kai had 6 $2-notes while Nat had 25 $2-notes. Don had only $20-notes.

1. Of the three boys, who had the most money? 
2. What was the difference in the total value of Kai and Nat's notes? 
3. Nat used all his $20-notes to buy a gift. He then had $550 less than Don. How many $20-notes did Don have?

(a)
The three boys had the same number of notes.
$2-notes have a lower denomination than $20-notes.

Since Don had only $20-notes, he had the most money.

(b)
Difference in the number of notes of different values
= 25 - 6
= 19

Difference in the value of $20-notes and $2-notes
= 20 - 2
= $18

Difference in the total value of Kai's and Nat's notes
= 19 x 18
= $342

(c)
Value of $2-notes that Nat had left
= 25 x 2
= $50

Total value that Don had
= 550 + 50
= $600

Number of $20-notes that Don had
= 600 ÷ 20
= 30

Answer(s): (a) Don; (b) $342; (c) 30