In [4]:

    

def find_missing(expression):
    expression_arr = expression.split(" ")
    a = expression_arr[0]
    b = expression_arr[2]
    c = expression_arr[4]
    
    diff = 0
    if a.isdigit():
        if b.isdigit():
            if c.isdigit():
                pass
            else:
                diff = int(a) + int(b)
                print a, "+", b, "=", diff 
        else:
            diff = int(c) - int(a)
            print a, "+", diff, "=", c
    else:
        diff = int(c) - int(b)
        print diff, "+", b, "=", c


    

In [5]:

    

find_missing("23 + 47 = machula")


    

    




23 + 47 = 70

In [6]:

    

find_missing("3247 + 5machula2 = 3749")


    

    




3247 + 502 = 3749

In [7]:

    

find_missing("machula13 + 75425 = 77038")


    

    




1613 + 75425 = 77038

In [ ]: