Answer:
$3.40
Step-by-step explanation:
"A bill" = "1 bill"
Possibile bills = $1, $5, $10, $20, $50, $100
4 × 1.65 = 6.6
$6.60 is more than $5, but less than $10
Since the student is only using a single bill, it must be the $10 bill
10 - 6.6 = 3.4
$3.40