A copying machine "P" can copy 135 pages in 9 minutes, P and Q together can copy 300 pages in 12 minutes. In what time Q can copy 80 pages? Choose the correct answer: A) 6 minute B) 7 minute C) 9 minute D) 8 minute E) 10 minute
P copying 135 pages in 9 minutes.   so in 1 minute P copying=135/9= 
<gadget id="calculator">135/9</gadget>
<output>15</output>
15 pages   P and Q both copying 300 pages in 12 minute.   so in 12 minute P coying the 12*15= 
<gadget id="calculator">12*15</gadget>
<output>180</output>
180 pages.   so Q copying alone=300-180= 
<gadget id="calculator">300-180</gadget>
<output>120</output>
120 pages.   according to question Q takes 12 minute for copying the pages.   so for 1 minute   120/12= 
<gadget id="calculator">  120/12</gadget>
<output>10</output>
10 pages.   because for 10 pages takes 1 minute   so 80 pages it's takes 8 minute   so ans is 8 minute.   ANSWER:8 minute
<result>D</result>
A copying machine "P" can copy 135 pages in 9 minutes, P and Q together can copy 300 pages in 12 minutes. In what time Q can copy 80 pages?