Interpret String?

Let’s say I have an equation in the form of a string (called equ), such as “(x/2)+4”.

how would I be able to translate the string into an actual equation, so i could have

myNum = (x/2)+4

eval(equ) does the trick - but the variables you use in the string (in this case x) must be defined when eval is called.

equ =  "(x/2) + 4"
x = 1.0
myNum = eval(equ)
print myNum