It would depened on whether she's covered by the Fast Food award or not.

I've just looked at the Award. Under the Modern Fast Food award the weekly rate for full time is $626.00 and she's entitled to 80% of that becuase she's 19. She should be getting about $13 an hour but then she might not be covered under the award. She could be getting 80% of the minimum wage, which is just under $14.50 so the $11ish an hour she's getting would be correct if that's the case.

She should ring Fairwork Australia and find out whether she's covered by the award, if it's a big business then she would definitely be covered but if it's a small business she may or may not be.