simplex-algorithm

Good morning, I have a question to an optimization problem I can't solve in R but in Excel: I would like to optimize the following situation (Transportation of material and people): Airline x1 can transport 50t of material and 500 people Airline x2 can transport 150t of material and 250 people 50x1 + 150x2 >= 900 -> Transportation of material min. 900 500x1 + 250x2 >= 2500 -> Transportation of people min. 2500 x1 is an airline with flight costs of 2500 per flight x2 is an airline with flight costs of 3500 per flight The costs should be minimized! x1>=0 x2>=0 Here is my solution in R (function