A farm used two harvesting machines, H and K, to harvest 100 acres of wheat. Harvesting machine H, working alone at its constant rate, harvested 40 acres of wheat in 8 hours. Then harvesting machine K was brought in, and harvesting machines H and K, working together at their respective constant rates, harvested the remaining acres of wheat in 4 hours. Harvesting machine K harvested how many acres of wheat per hour? Choose the correct choice:  A) 7  B) 8  C) 11  D) 13  E) 15
Rate of H = 4 acres/hr   Remaining land to be harvested = 100 - 40= 
<gadget id="calculator">100 - 40</gadget>
<output>60</output>
60   Rate of H and K= 60/4= 
<gadget id="calculator">60/4</gadget>
<output>15</output>
15 acres/hr   Rate of K= 15- 4= 
<gadget id="calculator">15- 4</gadget>
<output>11</output>
11   Answer: 11
<result>C</result>
A farm used two harvesting machines, H and K, to harvest 100 acres of wheat. Harvesting machine H, working alone at its constant rate, harvested 40 acres of wheat in 8 hours. Then harvesting machine K was brought in, and harvesting machines H and K, working together at their respective constant rates, harvested the remaining acres of wheat in 4 hours. Harvesting machine K harvested how many acres of wheat per hour?