Ifaequals the sum of the even integers from 2 to 80, inclusive, andbequals the sum of the odd integers from 1 to 79, inclusive, what is the value of a - b ?  Choose the correct option:
A) 1	B) 10	C) 19	D) 40	E) 21
This is a solution from Beatthegmat:   even numbers:   (80-2)/2 + 1= 
<gadget id="calculator">(80-2)/2 + 1</gadget>
<output>40</output>
40 even integers.   (80+2)/2= 
<gadget id="calculator">(80+2)/2</gadget>
<output>41</output>
41 is the average of the even set.   sum= avg*(#of elements) = 41*40= 
<gadget id="calculator">41*40</gadget>
<output>1_640</output>
1640= a   odd numbers:   (79-1)/2 + 1= 
<gadget id="calculator">(79-1)/2 + 1</gadget>
<output>40</output>
40 odd integers.   (79+1)/2= 
<gadget id="calculator">(79+1)/2</gadget>
<output>40</output>
40 is the average of the odd set.   sum= avg*(#of elements) = 40*40= 
<gadget id="calculator">40*40</gadget>
<output>1_600</output>
1600= b   a-b = 1640 - 1600= 
<gadget id="calculator">1640 - 1600</gadget>
<output>40</output>
40. Answer : 40
<result>D</result>
Ifaequals the sum of the even integers from 2 to 80, inclusive, andbequals the sum of the odd integers from 1 to 79, inclusive, what is the value of a - b ?