You've already solved the problem, you're just thinking too hard about how to translate that solution into code. If Ores holds the number of ores you generated, then you can compute amount of money ("gold") using your formula (4 * Ores) and store that in a separate variable repenting the gold:
int gold = 4 * Ores;
To integrate that into the rest of your game, since you already have a variable for holding the player's gold, you can just do
gold += 4 * Ores;
at the appropriate point. Do note that the += operator means, essentially, the same thing as gold = gold + (4 * Ores) here.
I suggest you take a look at a book called "Thinking in C++." Google for it -- it is freely available online and is generally considered a good introduction to the language.
There are some other things to note about your code as you've presented it so far that are not directly related to your question but will help you improve:
- You should include <cstdlib>, not <stdlib.h> (the former is more idiomatic C++)
- You declare all your variables up front, which is serviceable. But you don't initialize all of them, and you should generally always do that.
- You should consider packaging up all those variables related to the players into a struct representing a player's statistics and inventory, et cetera.
- You only need to call srand() once, at the start. You should not call it every time through your main loop as the frequency with which you reseed relative to the resolution of the timer you're using will actually cause your 'random' numbers to be extremely predictable.
- Consider using a switch statement instead of a series of if statements. Also consider breaking out each of the bits of code that handle the player's choice into their own function.
- void main() should be int main().
- == is the equality operator. = is the assignment operator. Code like if( pick = 5 )... doesn't do what you think it does.
- Try to be consistent with the capitalization of your identifier names. Use readable identifier names, not "x" and "n."
Some of the above suggestions may not make immediate sense to you, but keep them in mind as they will start to make sense when you reach the appropriate point in your education concerning the C++ language (in particular the notes about structs and functions).
Looking further, the logic of your game is also quite hard-coded (magic numbers, such as price points, are embedded into the code itself). This is generally considered a bad thing, although it is expected for a beginners programs to look like this for some time. As a bonus challenge question, think about how you might be able to reduce the amount of hard-coded numbers in the program.