.
A well known publishing house agreed to sell a stated number of copies of their book for RS 4500.
Had they sold 5 copies less for same amount they would have received RS 30 more for each copy. Find the number of copies sold?
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Let n = number of copies sold.
Then each copy was sold for RS 
.
Had they sold 5 copies less for the same amount, they would receive RS 
for each copy.
According to the condition,
+ 30 = 
.
Solve this equation for n. For it, multiply both sides by n*(n-5). You will get
4500*(n-5) + 30*n*(n-5) = 4500*n.
Simplify, and you will get a quadratic equation
= 
.
Apply the quadratic formula.
The equation has two roots. One root is negative, and it doesn't work. Another root is 30.
So, the number of copies sold is 30.
Please check the solution yourself.
Answer. The number of copies sold is 30.
