PSLE
Three boys, Ben, Sam and Joe had the same number of notes. Ben and Sam each had of mix of $20-notes and $10-notes. Ben had 3 $10-notes while Sam had 15 $10-notes. Joe had only $20-notes.

1. Of the three boys, who had the most money? 
2. What was the difference in the total value of Ben and Sam's notes? 
3. Sam used all his $20-notes to buy a souvenir. He then had $270 less than Joe. How many $20-notes did Joe have?

(a)
The three boys had the same number of notes.
$10-notes have a lower denomination than $20-notes.

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

(b)
Difference in the number of notes of different values
= 15 - 3
= 12

Difference in the value of $20-notes and $10-notes
= 20 - 10
= $10

Difference in the total value of Ben's and Sam's notes
= 12 x 10
= $120

(c)
Value of $10-notes that Sam had left
= 15 x 10
= $150

Total value that Joe had
= 270 + 150
= $420

Number of $20-notes that Joe had
= 420 ÷ 20
= 21

Answer(s): (a) Joe; (b) $120; (c) 21