A certain fraction is equivalent to 2/5. If the numerator of the fraction is increased by 4 and the denominator is doubled, the new fraction is equivalent to 1/3. What is the difference of the numerator and denominator of the original fraction?
Pick one:
A) 49
B) 9
C) 28
D) 26
E) 21
x/y = 2/5 -&gt; 1   (x+4)/2y = 1/3 -&gt; 2   Divide 1 by 2 :   =&gt; 2x/(x+4) = 6/5   =&gt; 5x = 3x + 12   =&gt; x = 6   =&gt; y = 5/2 * 6= 
<gadget id="calculator">5/2 * 6</gadget>
<output>15</output>
15   so x - y= 9   The answer is 9
<result>B</result>
A certain fraction is equivalent to 2/5. If the numerator of the fraction is increased by 4 and the denominator is doubled, the new fraction is equivalent to 1/3. What is the difference of the numerator and denominator of the original fraction?