I think c!
Because I got that on my homework and I got it right!!
C
She'd have to have given her more than 48 dollars to receive more than 30 dollars back
It can't be D because that implies she could've received exactly 30 dollars in change and the question states she received more than that.
45x + 50y = 2500
45(0) + 50y = 2500
50y = 2500
y = 50