A graphing calculator or spreadsheet program can do this for you. Below is a plot from the Desmos on-line graphing calculator.
If you are trying to find 3/4 of 28, multiply 3/4 (or 0.75( by 28), which equals 21.
3/4 • 28 = 21
Answer:
like 1000 maybe?
I think that's like a tough estimate