Okay, we know that the expenses for the day is 210.
Knowing this, and the price of the taco, we write the inequality:
3.25t > 210
t = number of tacos
Now divide both sides by 3.25:
t > 64.62 (rounded)
Because a taco stand can't sell a fraction of a taco, we know that the taco stand has to sell more than 65 tacos for a profit.