Question

shopkeeper buys x books for 720.
) Write the cost of 1 book in terms of x.
) If the cost per book be * 5 less, the number of books that could be bought for
be 2 more
rite down the nation in and solve it to find​

Answer 1

Answer:

Step-by-step explanation:

Let X= cost of a book, Y= number of books you buy.

Then XY=$720 (given).

 

If cost of books is reduced by $5 (then cost is X-5),  you could buy 2 more books (Y+2 books) for same price

 

So (X-5)(Y+2) = 720

 

From first equation: Y=720/X

Then Y+2 = 720/X+2 = (720+2X)/X

 

and (X-5)(720+2X)/X=720

(X-5)(720+2X) = 720X

 

720X + 2X^2 - 5*720 -10X = 720X

2X^2 - 10X - 3600 = 0

X^2 - 5X - 1800 = 0

 

This factors to: (X-45)(X+40) = 0

 

and has solutions X=-40 and X=45.  X=-40 does not makes sense since the price cannot be negative, so the original price of the books is $45.

 

Y = number of books = 720/45 = 16 books