At the end of the month, a certain ocean desalination plant’s reservoir contained 40 million gallons of water. This amount is one fifth of the normal level. If this amount represents 80% of the reservoir’s total capacity, how many million gallons short of total capacity is the normal level? Choices.
A) 20  B) 30  C) 40  D) 50  E) 60
the Q talks of total capacity, normal level, present level, shortage etc..   so it is all about not going wrong in these terms   40 MG= 80% of Total..   total = 40/.8= 
<gadget id="calculator">40/.8</gadget>
<output>50</output>
50MG..   Normal level= 1/5 of 50=10MG..   shortage of normal level=50-10= 
<gadget id="calculator">50-10</gadget>
<output>40</output>
40MG..   40
<result>C</result>
At the end of the month, a certain ocean desalination plant’s reservoir contained 40 million gallons of water. This amount is one fifth of the normal level. If this amount represents 80% of the reservoir’s total capacity, how many million gallons short of total capacity is the normal level?