The average of 13 result is 20. Average of the first 8 of them is 20 and that of the last 8 is 40. Find the 8th result? Choose the correct choice from the following:  A) 35  B) 37  C) 46  D) 90  E) 100
Sum of all the 13 results = 13 * 20= 
<gadget id="calculator">13 * 20</gadget>
<output>260</output>
260   Sum of the first 7 of them= 8 * 20= 
<gadget id="calculator">8 * 20</gadget>
<output>160</output>
160   Sum of the last 7 of them= 8 * 40= 
<gadget id="calculator">8 * 40</gadget>
<output>320</output>
320   So, the 8th number= 260 + 160 - 320= 
<gadget id="calculator">260 + 160 - 320</gadget>
<output>100</output>
100.   100
<result>E</result>
The average of 13 result is 20. Average of the first 8 of them is 20 and that of the last 8 is 40. Find the 8th result?