question: To heat during the winter, Ali ordered 850 kilos of coal. The coal is delivered in 50 kg bags, costing $18 per unit. How much does his order cost?
answer: The number of bags Ali ordered is 850 kg/ 50 kg/bag = <<850/50=17>>17 bags
  The total order cost is 17 bags x $18/bag = $<<17*18=306>>306
  #### 306