The dress costs $52.50 more that she has , so she has to earn that much money by babysitting so that she can have the full amount of dress.
She charges $5.50 for an hour
So for $52.50 she has to work for 52.50/5.50 hours
52.50 divided by 5.50 equals 9.55 hours
So Sid has to babysit for 9.55 hours to earn $52.50 so that she can buy the dress.
