On Tuesday, Donovan earned $9 for 2 hours of babysitting. On Saturday, he babysat for the same family and earned $31.50. How many hours did he babysit on Saturday?
\(2h=\$9\) \(1h=\$4.5\) then we have to divide \(31.5\) by \(4.5\) \(31.5/4.5=\frac{31.5}{4.5}=7\) it means Donovan babysit children of this family for 7 hours