David has d books, which is 2 times as many as Jeff and 1/2 as many as Paula. How many books do the three of them have altogether, in terms of d?
Choose the correct answer
A) 5/6*d	B) 7/3*d	C) 10/3*d	D) 7/2*d	E) 9/2*d
Although we could plug in a real value for d, the problem can be just as easily solved by setting up equations. However, let’s start by defining some variables. Since we are given that David has d books, we can use variable d to represent how many books David has.   number of books David has = d   number of books Jeff has = j   number of books Paula has = p   We are given that David has 3 times as many books as Jeff. We can now express this in an equation.   d = 2j   d/2 = j   We are also given that David has ½ as many books as Paula. We can also express this in an equation.   d = (1/2)p   2d = p   Notice that we immediately solved forj in terms of d and p in terms of d. Getting j and p in terms of d is useful when setting up our final expression. We need to determine, in terms of d, the sum of the number of books for David, Jeff, and Paula. Thus, we have:   =d + d/2 + 2d   =7d/2   The answer is 7/2*d
<result>D</result>
David has d books, which is 2 times as many as Jeff and 1/2 as many as Paula. How many books do the three of them have altogether, in terms of d?