The Always Works approach for percent problems like these is to set it up as a fraction problem:
percentage / 100 = part / whole
For any problem, you'll know two of these, and have to find the last. In this case you know the partial price of the suit - that is, you know the price that is just a part of the full price. That's your "part". You also know the percentage it is - it's a 20% discount, so you paid 80% of the full price. That's your "percentage". What you want to know is the full price, that's the "whole". Now you can set it up like this:
80 / 100 = 276 / x
Now it's just a fraction problem! Using this set up will help you with a LOT of percentage problems, and I really recommend it!
So, that's how you set it up, and if you know how to solve it from there then you can stop reading now. However, I know many students panic in the face of fractions, so let me walk you through how to actually solve for x:
80 / 100 = 276 / x
What you're going to do is called cross multiplication, and a lot of students remember it as "the butterfly thing" : D You're going to multiply the bottom of each fraction by the top of the fraction on the other side:
80x = 276 * 100
80x = 27600
Now it's just a matter of getting the 80 off the x! The 80 is being multiplied by the x, so to get it off we use division:
80x/80 = 27600 / 80
x = 27600/80
Grab a calculator and see that 27600/80 = 345, so we have:
x = 345
That's the full price of the suit, so your final answer is $345!