Hey, just needing some help here:

How much simple interest would be paid on a $700 loan for 5 years (60 months i think, it's easier if you convert to months) at a rate of interest 18%: [my workings: prt= 700x18x60/100 is that right?] how would i do it?

and also

Sarah sold her bike for $300 which is 80% of the amount she originally paid for it. What did she pay originally for it?