In an apartment building that has 490 units, 4 out of every 7 units are currently rented, including 1/6 of the one-bedroom units. If, of the rented apartments, there is a 6:1 ratio of two-bedroom units to one-bedroom units, and the building only consists of two-bedroom and one-bedroom units, how many two-bedroom units are not rented? Choose the correct choice
A) 50 B) 70 C) 10 D) 105 E) 140
Rented = 4/7*490= 
<gadget id="calculator">4/7*490</gadget>
<output>280</output>
280.   Rented two-bedroom= 6/7*280= 
<gadget id="calculator">6/7*280</gadget>
<output>240</output>
240;   Rented one-bedroom= 1/7*280= 
<gadget id="calculator">1/7*280</gadget>
<output>40</output>
40 (or 280-240= 
<gadget id="calculator">280-240</gadget>
<output>40</output>
40).   Rented one-bedroom units are 1/5 of all one-bedroom: 1/6*{All one bedroom}= 40 --&gt; {All one-bedroom} = 240.   {All two-bedroom} = 490 - 240= 
<gadget id="calculator">490 - 240</gadget>
<output>250</output>
250.   Two-bedroom not rented= 250 - 240= 
<gadget id="calculator">250 - 240</gadget>
<output>10</output>
10.   Answer: 10.
<result>C</result>
In an apartment building that has 490 units, 4 out of every 7 units are currently rented, including 1/6 of the one-bedroom units. If, of the rented apartments, there is a 6:1 ratio of two-bedroom units to one-bedroom units, and the building only consists of two-bedroom and one-bedroom units, how many two-bedroom units are not rented?