from tkinter import*
def nizvodno():
    fr=int(f1.get())+ int(f2.get())
    f=Label(p,text=(fr,'N'),font=14)
    f.place(x=80,y=210)
    
    return
def uzvodno():
    fr=int(f2.get())- int(f1.get())
    f=Label(p,text=(fr,'N'),font=14)
    f.place(x=225,y=210)
    return
p=Tk()
p.title('Sila toka rijeke')
p.config(width=360, height=260)
naslov=Label(p,text='SILA NA ČAMCU',font=14)
naslov.place(x=120,y=10)
# lijevo

sila_tr=Label(p,text='Sila toka rijeke (N):')
sila_tr.place(x=60,y=70)
f1=Entry(p,font=14)
f1.place(x=180,y=70,width=60)


sila_mc=Label(p,text='Sila motora čamca (N):')
sila_mc.place(x=35,y=110)
f2=Entry(p,font=14)
f2.place(x=180,y=110,width=60)


g1=Button(p,text='NIZVODNO',command=nizvodno)
g1.place(x=50, y=170, width=100)

# desno

g2=Button(p,text='UZVODNO',command=uzvodno)
g2.place(x=200, y=170, width=100)

p.mainloop()