Formula, Objective and Constraints
library(lpSolve)
obj.fun<-c(420,360,300,420,360,300,420,360,300)
constr<-
matrix(c(1,1,1,1,1,1,1,1,1,20,15,12,20,15,12,20,15,
12,1,1,1,1,1,1,1,1,1,.0013,-.001,
.0013,-.002,
nrow=11,byrow=TRUE))
constr.dir<-c("<=","<=","<=","<=","<=","<=","<=","<=","<=","=","=")
rhs<-c(750,900,450,13000,12000,5000,900,1200,750,0,0)
probsol<-lp("max",obj.fun,constr,constr.dir,rhs,compute.sens = TRUE)
probsol$solution
1] 0 0 0 0 0 0 0 1 0
This is my answer, but I know it's wrong, and I don't know what I'm missing.