Answer: 16 hours
Explanation:
We will write a system of equations to help us solve. Let x be equal to the number of hours worked at the college bookstore, and y be equal to the number of hours worked at Papa Gino's.
First, we will write an equation for the money earned. Then, we will write one for the hours worked.
8.25x + 9.25y = 247
x + y = 28
Now, we will will substitute the second equation into the first and solve for the hours worked at Papa Gino's last week, equal to y.
x + y = 28 ➜ x = -y + 28
8.25x + 9.25y = 247
8.25(-y + 28) + 9.25y = 247
-8.25y + 231 + 9.25y = 247
y + 231 = 247
y = 16
Rosemary worked 16 hours at Papa Gino's last week.