Of the four numbers, whose average is 80, the first is one-fourth of the sum of the last three. The first number is ?	Select the correct option.
A) 28 B) 64 C) 11 D) 48 E) 10
Explanation:   Let the first number be x,   Then, sum of the four numbers = x + 4x = 5x.   so, 5x/4 = 80 or x = (80 * 4) / 5= 
<gadget id="calculator">(80 * 4) / 5</gadget>
<output>64</output>
64   Answer: 64
<result>B</result>
Of the four numbers, whose average is 80, the first is one-fourth of the sum of the last three. The first number is ?