Jason is saving up for a skateboard and helmet. The skateboard is $45.50 with tax and the helmet is $18.25 with tax. He earned 1/3
of the money by mowing lawns and the rest by babysitting. How much did Jason earn babysitting?
The total cost of the skateboard and helmet is $45.50 + $18.25 = $<<45.50+18.25=63.75>>63.75.
So, Jason earned $63.75 x 1/3 = $<<63.75*1/3=21.25>>21.25 mowing lawns.
Therefore, Jason earned $63.75 - $21.25 = $<<63.75-21.25=42.50>>42.50 babysitting. Answer: \boxed{42.50}.