a man is 20 years older than his son . in two years , his age will be twice the age of his son . the present age of the son is ?
n0 = 20.0
t0 = 2.0 * 2.0
t1 = 2.0 - 1.0
t2 = t0 - 2.0
t3 = n0 - t2
answer = t3 / t1
print(answer)