If r and s are positive integers and r-s=6, which of the following has the greatest value Q?
Select the correct option
A) 2r
B) 2s
C) r +s
D) 2r-s
E) 2s-r
The simplest way to do this is to assume values.   We are told that r and s are positive integers Q.   Also, r-s = 6 =&gt; r = 6+s   Hence r is 6 more than s.   Let s be 10. Hence r = 16.   Option 2r: 2r = 2*16= 
<gadget id="calculator">2*16</gadget>
<output>32</output>
32   Option B: 2s= 2 * 10= 
<gadget id="calculator">2 * 10</gadget>
<output>20</output>
20   Option C: r + s= 16 + 10= 
<gadget id="calculator">16 + 10</gadget>
<output>26</output>
26   Option D: 2r - s= 2(16) - 10 = 32 - 10= 
<gadget id="calculator">32 - 10</gadget>
<output>22</output>
22   Option E: 2s - r= 2(10) - 16 = 20 - 16= 
<gadget id="calculator">20 - 16</gadget>
<output>4</output>
4   Hence option 2r is the greatest.
<result>A</result>
If r and s are positive integers and r-s=6, which of the following has the greatest value Q?