Python - how to assign 1 output to multiple inputs, to then use that output in an equation

Question

So i have something like this:

x = input("input something(suggested inputs):")
x = x.replace("some input","3")
x = x.replace("some other input","3")
x = int(x)
solution = x*(g**3)/(4*x) #some equation

I need efficient way to set multiple keywords like "big" or "in the kitchen" to one value that then could be used in an equation, and i feel like what i have is not the best way to do this.