jmc

Jason borrowed money from his parents to buy a new surfboard. His parents have agreed to let him work off his debt by babysitting under the following conditions: his first hour of babysitting is worth \1$,thesecondhourworth$\$2$, the third hour \3$,thefourthhour$\$4$, the fifth hour \5$,thesixthhour$\$6$, the seventh hour \1$,theeighthhour$\$2$, etc. If he repays his debt by babysitting for 39 hours, how many dollars did he borrow?