help

import Tkinter as tk
from random import randint

def randomchance():
    num = randint(1,100)
    if num <= 60:
        chance = 2
    elif num <= 90 and num > 60:
        chance = 3
    else:
        chance = 4

def onClick():
    global cash, cashclick
    cash += cashclick
    totalcash.configure(text="Total Cash: $" + str(cash))
def evolve():
    global cash, cashclick, chance
    toplevel = tk.Toplevel()
    confirmtxt = tk.Label(toplevel, text="Are you sure you want to evolve? You will lose all your progress, but money earned per click will increased either 2x, 3x, or 4x.", height = 0, width = 100)
    def notevolve():
        toplevel.destroy()
    def doevolve():
        global cash, cashclick, chance
        cash -= cash
        randomchance()
        cashclick *= chance
        totalcash.configure(text="Total Cash: $" + str(cash))
        toplevel.destroy()

    confirmA = tk.Button(toplevel, text="Yes Evolve", command=doevolve)
    confirmB = tk.Button(toplevel, text="Don't Evolve", command=notevolve)
    confirmtxt.pack()
    confirmA.pack(side = tk.LEFT)
    confirmB.pack(side = tk.LEFT)
def destroywindow():
    root.destroy()

chance = 1
cash = 0
cashclick = 100
root = tk.Tk()

root.title("Test")

totalcash = tk.Label(text="Total Cash: $" + str(cash), fg = "green", font=('Arial',40))
earncash = tk.Button(text="Work",command=onClick)
quitgame = tk.Button(text="QUIT GAME.", fg = 'red',command=destroywindow)
evolveB = tk.Button(text="Evolve",command=evolve)

totalcash.pack()
earncash.pack()
evolveB.pack()
quitgame.pack()
root.mainloop()