PSLE
Three boys, Don, Tim and Ari had the same number of notes. Don and Tim each had of mix of $20-notes and $5-notes. Don had 11 $5-notes while Tim had 18 $5-notes. Ari had only $20-notes.

1. Of the three boys, who had the most money? 
2. What was the difference in the total value of Don and Tim's notes? 
3. Tim used all his $20-notes to buy a gift. He then had $470 less than Ari. How many $20-notes did Ari have?

(a)
The three boys had the same number of notes.
$5-notes have a lower denomination than $20-notes.

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

(b)
Difference in the number of notes of different values
= 18 - 11
= 7

Difference in the value of $20-notes and $5-notes
= 20 - 5
= $15

Difference in the total value of Don's and Tim's notes
= 7 x 15
= $105

(c)
Value of $5-notes that Tim had left
= 18 x 5
= $90

Total value that Ari had
= 470 + 90
= $560

Number of $20-notes that Ari had
= 560 ÷ 20
= 28

Answer(s): (a) Ari; (b) $105; (c) 28