in 7 given numbers , the average of first 4 numbers is 4 and that of last 4 numbers is also 4 . if the average of these 7 numbers is 3 , the fourth number is ?
n0 = 7.0
n1 = 4.0
n2 = 4.0
n3 = 4.0
n4 = 4.0
n5 = 7.0
n6 = 3.0
t0 = n1 * n1
t1 = n0 * n6
t2 = t0 + t0
answer = t2 - t1
print(answer)