Problema Solution
A man buys a number of golf balls from a shop for $400. A week later the shop has a sale and the golf balls cost $4 less. At the sale price the man could have bought 5 more golf balls for the same amount of money. Calculate how many golf balls the man originally bought.
Answer provided by our tutors
let he bought x balls
cost of each ball = 400/x
cost later = 400/x - 4
=> (400/x - 4) * (x+5) = 400
=> (100 - x)(x+5) = 100x
=> -x^2 +100x - 5x + 500 = 100x
=> x^2 + 5x - 500 = 0
=> x = 20