Let x specify the number of 16 ounce serving
If you buy the mug you acquire the first serving including the mug.
So the price of x is:
295 + 50(x - 1)
the x - 1 here shows that the first serving with the mug.
And then count the whole thing in cents.
The fee of throwaway cups is 85x
So breakeven is computed by:
295 + 50(x - 1) = 85x
295 + 50x - 50 = 85x
245 = 35x
x = 245/35 = 7
Checking this will give us:
mug 2.95 + 50*6 = 5.95
disposable
8.5*7 = 5.95
So the answer is D.