Algebra @
posted by Trisan .
Sally invested a total of $4500, some at 9% per year and the rest at 6% per year. The return from the 9% investment exceeds that from the 6% investment by $180. How much did she invest at each rate?

A boat travels 60 km upstream and back again in 8 hours. If the speed of the boat is 16 km/h, what is the speed of the current? Please Show Work