TypeError: Not supported between instances of 'function' and 'int'

[Gribouillis]

systolic_blood_pressure is a function. It must be called with parentheses ()

elif systolic_blood_pressure() >= 180:

Apart from that, pythonistas usually avoid eval() for security reasons. In your case, you could use ast.literal_eval() instead of eval(). Import ast first. Also as you're entering numbers, you could simply use int() or float(), which is better than eval

b = float(input("Please enter SBP: "))