Hey guys, I need help doing a project, and I can't seem to get this one right. I was wondering if someone could guide me through the steps so I can complete it?

The form looks like this:


And needs to calculate prices, with labels being the output like this:


And here is a table of how the prices should be:

Quantity | | Price per widget
1 - 10 | | $20.00
11 - 20 | | $18.00
21 - 30 | | $16.00
31 + | | $14.00

My apologies if this doesn't seem like it makes sense, I'm rushing but I will gladly explain for specifics.