C1= 0.05
C2= 0.05
C3= 0.05

Q= C2*C3/C1

x=0
dx=0.00001
while Q < 0.31 :
    C1=C1-dx
    C2=C2+dx
    C3=C3+dx
    Q=C2*C3/C1
    x=x+dx

while Q > 0.31 :
    C1=C1+dx
    C2=C2-dx
    C3=C3-dx
    Q=C2*C3/C1
    x=x+dx
print('Qeq=',Q)
print('[Fe3+]=', C1, 'mol/L')
print('[Ag+]=', C2, 'mol/L')
print('[Fe2+]=', C3, 'mol/L')