An alloy weighing 24 ounces is 70 percent gold. How many ounces of pure gold must be added to create an alloy that is 80 percent gold?
Choose one:
A) 6
B) 9
C) 12
D) 24
E) 48
In 24 ounces, gold is 24 * (70/100)= 
<gadget id="calculator">24 * (70/100)</gadget>
<output>84/5 = around 16.8</output>
16.8 ounces. Now we add x ounces of pure gold to make it 90% gold.   So 16.8 + x= (24 + x)* 80/100 =&gt; x =12.   Answer is 12.
<result>C</result>
An alloy weighing 24 ounces is 70 percent gold. How many ounces of pure gold must be added to create an alloy that is 80 percent gold?