If the rabbit food costs $12 a week, then the parrot food costs $30 - $12 = $18 a week.
Julia has the parrot for 3 weeks, so she spent 3 weeks * $18/week = $<<3*18=54>>54 on her.
The rabbit is her only for 5 weeks, so she spent 5 weeks * $12/week = $<<5*12=60>>60 on him.
In total, Julia spent $54 + $60 = $<<54+60=114>>114 on food for her animals.
#### 114