## DATA

revenue <- matrix(data = c(190, 140, 1926, 14, 143, 325 ,19, 293,
                           1491, 162, 682, 14, 852, 56, 659, 829,
                           140, 609, 120, 87),
                  nrow = 4, byrow = T,
                  dimnames =  list(c("Tea", "Coffee", "Water", "Milk"),
                                   c("Johnver", "Vanston" ,"Danbree",
                                     "Vansey", "Mundyke")))

expenses <- matrix(data = c(120, 65, 890, 54, 430, 300, 10, 23, 802,
                            235,50, 299, 1290, 12, 145, 67, 254, 89,
                            129, 76),
                   nrow = 4, byrow = T,
                   dimnames =  list(c("Tea", "Coffee", "Water", "Milk"),
                                    c("Johnver", "Vanston" ,"Danbree",
                                      "Vansey", "Mundyke")))


## FUNCTION

coms <- function(rvn, exs, prc = 0.062){
    profit <- revenue - expenses; profit[profit < 0] <- 0
    comm.vec <- floor(colSums(profit * prc))
    commissions <<- matrix(data = comm.vec, nrow = 1,
                           ncol = length(comm.vec),
                           dimnames = list("Commission", colnames(rvn)))
    commissions
}

## CHALLENGE CASE

coms(rvn = revenue, exs = expenses)