Answer:
Tyree has spend 3 hours on the bike.
Step-by-step explanation:
For starters, he has already paid $4 to ride the bike. For each hour, $9 would be added to the $4; for example:
$4 + $9/hr
$13 after an hour + $9
$22 after 2 hours + $9
$31 after 3 hours.
