I am having a problem creating a formula for the following criteria:

I have 3 cells that depend on user input, the results of that input
determine the action of the conditional formating of another cell.
Whereas the 3 cells that required user input can equal any whole number from
0 to infinity.
the first cell determines a given quantity of an item "Item A"
the second cell is the quantity of another item "Item B"
the third cell is the number of Item B that is needed for the operation,
whereas I need to have a certain quantity in Item A in order to have a
certain quantity in Item B
Meaning that if I want 1 of Item B, I need to have 50 of Item A
Once I have 1 of Item B, I will require 50 more in Item A
The conditional format will indicate when I have aquired enough of Item A in
order to obtain more of Item B.
Therefore if the condition is false, nothing changes until the quantities
are in the acceptable ranges.
I can make the formula work somewhat but in reverse of what I wish to do
To make it easier to understand, I will use the following example:

Given the following:
Item A = Cell E300
Item B = Cell F302
Quantity required = Cell E302

If the quantiy required of Item A is 1 then I need 50 of Item A
Therefo If E302=1 then E300 must equal 50, however if I already have 1 of
Item B then E300 will have to equal 100 and so on.

=IF(E302=1,((E300=50)+(F302*50)),0)
=IF(((E302=50)+(F302*50)),E302=1,0)
both of these require an input from E302 before they will work