Not necessarily an IF function, but a condition being met

I am trying to get a cell in excel to display a different cell's value for a value of less than 20, and display a different cell's value if its results are 20 and greater. what function or formula would i use.

I want cell j23 to display value for cell b23 if value is under 20, or if value is 20 and greater to display cell value f23.

All help appreciated.