It takes 6 tons of copper ore and 15 tons of iron ore to make one ton of alloy A. How many tons of alloy A can be made from 60 tons of copper ore and 90 tons of iron ore? Select.
A) 4  B) 5  C) 6  D) 7  E) 8
Yes, you need copper ore:iron ore in the ratio 6:15. Total 21 tons of the mix in this ratio will give 1 ton of alloy A.   If you have 60 tons of copper ore, it is enough for 60/6= 
<gadget id="calculator">60/6</gadget>
<output>10</output>
10 tons of alloy A.   If you have 90 tons of iron ore, it is enough for 90/15= 
<gadget id="calculator">90/15</gadget>
<output>6</output>
6 tons of alloy A.   Since iron ore is available for only 6 tons of alloy A, you can make only 6 tons of alloy A.   The leftover copper ore alone cannot make any alloy A and hence will be leftover only.   Answer must be 6.   (6)
<result>C</result>
It takes 6 tons of copper ore and 15 tons of iron ore to make one ton of alloy A. How many tons of alloy A can be made from 60 tons of copper ore and 90 tons of iron ore?