In order to complete a reading assignment on time, Terry planned to read 60 pages per day. However, she read only 30 pages per day at first, leaving 480 pages to be read during the last 6 days before the assignment was to be completed. How many days in all did Terry have to complete the assignment on time?  Choose the correct choice from the following choices.
A) 10  B) 8  C) 6  D) 12  E) 14
D=60*X - according to the plan, assignment to be completed on time reading 60 pages per day for next X days. But, Terry's plans changed so she read as follow:   30 pages for first Y days and 480 pages for last 6 days, we get these equations:   30*Y+480=60*X   X-Y=6 ---------&gt;&gt;X planned number of days, Y - actually used reading 30 pages per day and 6 leftover days used to complete a lump 780 pages   From above we find that X=Y+6 and 30Y+480=60Y+360 or 30Y=120 ---&gt;&gt;&gt;&gt;&gt; Y=4, hence X=10   10nswer : 10
<result>A</result>
In order to complete a reading assignment on time, Terry planned to read 60 pages per day. However, she read only 30 pages per day at first, leaving 480 pages to be read during the last 6 days before the assignment was to be completed. How many days in all did Terry have to complete the assignment on time?