A lemonade stand sold only small and large cups of lemonade on Tuesday. 3/5 of the cups sold were small and the rest were large. If the large cups were sold for 7/12 as much as the small cups, what fraction of Tuesday's total revenue was from the sale of large cups?
Choose the correct answer
A) (a) 7/16
B) (b) 7/15
C) (c) 10/21
D) (d) 7/25
E) (e) 1/2
This problem is very good example how easy and quick plug-in method might be.   Let the total # of cups be 10.   # of small cups sold 3/5*10= 
<gadget id="calculator">3/5*10</gadget>
<output>6</output>
6;   # of large cups sold  10-6= 
<gadget id="calculator"> 10-6</gadget>
<output>4</output>
4;   Let the price of small cup be $6, then the price of larges cup would be 7/12*6=$7/2;   Revenue from small cups: 6*$6=$36;   Revenue from large cups cups: 4*$7/2  6* 6= 
<gadget id="calculator">  6* 6</gadget>
<output>36</output>
$36;   Revenue from large cups cups: 4*$7/2=$14;   Fraction of total revenue from large cups: 14/(36+14) 4* 7/2= 
<gadget id="calculator"> 4* 7/2</gadget>
<output>14</output>
$14;   Fraction of total revenue from large cups: 14/(36+14)=7/25.   Answer: (d) 7/25.
<result>D</result>
A lemonade stand sold only small and large cups of lemonade on Tuesday. 3/5 of the cups sold were small and the rest were large. If the large cups were sold for 7/12 as much as the small cups, what fraction of Tuesday's total revenue was from the sale of large cups?