Answer: Yes, $9.
Explanation:
From what I understand, since the table isn't showing: \
Dinner bill $25:$4.50 tip, $30:$5.40, etc..
To find if Bill is proportional, we need to find the rate of each tip to Bill and see if they match.
$25/$4.50 =5.555555555...
$30/$5.40 =5.555555555...
$35/$6.30 =5.555555555...
$40/$7.20 =5.555555555...
The rate is the same for each one, so yes, the amount of the donation proportional to the dinner bill.
To find the donation for a bill of $50, divide by the rate we found above.
