How would a decrease in u. s. capital investment by peruvians impact the supply of the peruvian sol and the u. s. dollar price of the sol?

A decrease in U. S. capital investment reflects a decrease in the demand for the U. S. dollar, therefore you would be seeing a fall in the price of the dollar in terms of the Peruvian sol.

The supply may or may not remain unchanged, as it is unclear whether the Peruvians convert the U. S. dollar back into the sol or not.