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 and the rest by babysitting. How much did Jason earn babysitting?
Jason earned a total of $45.50 for the skateboard + $18.25 for the helmet = $<<45.5+18.25=63.75>>63.75.
Mowing earned Jason $63.75 x 1/3 = $<<63.75*1/3=21.25>>21.25.
Thus, Jason earned $63.75 - $21.25 = $<<63.75-21.25=42.5>>42.5 babysitting. Answer: \boxed{42.5}.