sumador

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
import tkinter as tk
ventana = tk.Tk()
ventana.config(width=400, height=600, bg="slate gray")
ventana.title("Ventana")

def sumar():
    a = float(caja_a.get())
    b = float(caja_b.get())
    suma = a + b
    total.set(str(suma))

total = tk.StringVar()    # total = "0"
total.set("0")

caja_a = tk.Entry(font = ["arial",15,"bold"], justify="right")
caja_a.place(x=20, y=50, width=100, height=25)

caja_b = tk.Entry(font=["arial",15,"bold"], justify="right")
caja_b.place(x=220, y=50, width=100, height=25)

caja_c = tk.Entry(
                font =["arial",15,"bold"],
                justify="right",
                state= tk.DISABLED,
                textvariable = total,
                )




caja_c.place(x=150, y=100, width=100, height=25)

boton = tk.Button(text="Sumar", command=sumar)
boton.place(x=150, y=200, width=100, height=40)



ventana.mainloop()