I don't get this question plz help?

Question

A sports goods store owner bought a quantity of basketballs for $750. Through a special discount from the manufacturer he is told he can get 10 extra basketballs and save $15 off the price of each ball while still spending $750.
Answer the following questions based on the above information:

What two variables is the original cost of $750 based on?

Write a let statement for each variable
Let x be………..
Let y be………..

Write an equation for the total cost of the balls after the manufacturers discount.

Answer 1

The two variables are the quantity x, and the price Y.
Therefore, let
X = the quantity
Y = the price

The original equation representing the original quantity and price will therefore be:

XY = $750

To answer your question as to the new equation involving the new price and the new purchase quantity:

(x+10)(y-15)= 750 The Answer

To solve for this two-variable equation, we need to use
the other equation (original price and quantity) so we may reduce the new equation to an equation with one unknown:

X = 750/y Additional Help to Solve for X and Y

I hope I was able to teach you how to go about the problem involving two unknowns.

Have a great day!

Answer 2

Let B = the number of balls
Let P = the price per ball
these are easier to remember than x and y.
Consider the units of B and P:
B is in balls
P is in $ / ball
Multiplying B * P = balls * dollars / ball = dollars.
The original equation states that
B * P = 750
The second equation states that
(B + 10) * (P - 15) = 750
i.e. 10 more balls at $15 less per ball

Taking this one more step: FOIL the second equation to arrive at:
BP + 10P - 15B - 150 = 750, but we know that BP already equals 750, so
750 + 10P - 15B - 150 = 750
subtracting 750 from each side we get
10P - 15B - 150 = 0 or
10P - 15B = 150
Substituting B = 750 / P we see
10P - 15 (750/P) = 150
Divide out by 10 and multiply both sides by P
P^2 - 1125 = 15P or rearranging
P^2 - 15P - 1125 = 0
Now you need to solve this equation for P:
Using the Quadratic Formula:
P = [15 +/- sqrt(225 - 4(1)(-1125))] / 2
P = [15 +/- sqrt(4725)] / 2
P = [15 +/- 68.739] / 2
P = 83.739 / 2 = 41.87 or
P = -53.739 / 2 = -26.87
Clearly the Price cannot be negative, so the Price must be $41.87 and the number of balls must be 750/41.87 = 17.9

Check: 41.87 * 17.9 = 750 yes!
(41.87-15)*(17.9+10) = 26.87 * 27.9 = 750 yes!

Tiny issue: You can't really buy 17.9 balls, so you might need to round to 18, but this will mess up the answer. Oh well....

Answer 3

Let x be the number of the balls.
Let y be the price of each ball.

xy=750


After discount the equation is
(x+10)(y-15)=750

or
750+15x+10y-150=750

15x+10y=150

or

3x+2y=30