say you had 300 of x and 300 of y and you needed to get 800 dollars from both x and y, if they sold x for 4$ and y for 2$ how many of of x and y do they need to sell

Let x be the number of items for X and y be the number of items for Y that need to be sold.

We have the following two equations:

4x + 2y = 800 (since they want to make 800 dollars in total)

x + y = 300 (since they have only 300 of each item)

We can solve this system of equations to find the values of x and y:

First, isolate y in the second equation:

y = 300 - x

Now substitute this expression for y in the first equation:

4x + 2(300 - x) = 800

4x + 600 - 2x = 800

2x = 200

x = 100

Now substitute this value of x back into the expression for y:

y = 300 - 100

y = 200

So they need to sell 100 of X and 200 of Y to make 800 dollars.