robert ' s salary was increased by 50 % and subsequently decreased by 10 % . how much percentage does he gain ?
n0 = 50.0
n1 = 10.0
t0 = n0 + 100.0
t1 = n1 * 2.0
t2 = 100.0 - 10.0
t3 = t0 / 100.0
t4 = t2 / 100.0
t5 = t3 * t4
t6 = t5 * 100.0
t7 = t6 - 100.0
answer = t7 - t1
print(answer)