An alloy weighing 16 ounces is 50% gold. How many ounces of pure gold must be added to create an alloy that is 80% gold?  Choose the correct choice from the following choices
A) 24  B) 18  C) 9  D) 27  E) 18
An alloy of 16oz which is 50% gold means there is 8 oz of gold. To get to an alloy that is 80% gold, let's use this expression: (8 + x)/(16 + x) = 0.8 with x representing the amount of pure gold that must be added to get to 80%. The expression we are using represents the new total weight of pure gold over the new total new weight of the alloy and this fraction should represent 80% or 0.8. you will see that 24 is the correct answer, as  32/40= 
<gadget id="calculator"> 32/40</gadget>
<output>4/5 = around 0.8</output>
0.8   Choose 24
<result>A</result>
An alloy weighing 16 ounces is 50% gold. How many ounces of pure gold must be added to create an alloy that is 80% gold?