gas_cost <- function(price_per_gal=6, fuel_efficiency=30, Trip_Miles = 50){
  gas_cost <- ceiling(price_per_gal*(fuel_efficiency^{-1})*Trip_Miles) # rounded to the next dollar (whole int.)
  cat(paste0(gas_cost, "$ Dollars for Gas"))
  }
gas_cost()
## 10$ Dollars for Gas