need help with motion problem

I have been having no trouble with motion problems when using d=r/t, and drawing a picture and using values in rows and columns, but this one problem has got me stumped and I think I may be making it more diffucult than it is:

A motorist set out at a certain rate, which he continued for 2 hours. He then encountered a detour which slowed him down to half his original rate. The detour took him 1 hour. After the detour he increased his speed 35 miles per hour (over what he was making during the detour) and after continuing ½ hour more he had gone 155 miles. What was his original rate.

Can anyone help me out on this one?

I have been using x+.5x+.85x=155/3.5 without success.

Thanks

Try it like so:

\(\displaystyle \L\\2r+\frac{r}{2}+\frac{1}{2}(\frac{r}{2}+35)=155\)

Now, solve for r.