Python - example

import pandas as pd

data = [
    [40, 60, 3, 3],
    [60, 80, 8, 11],
    [80, 100, 30, 41]
]

df = pd.DataFrame(data)

df['average'] = df[ [0,1] ].mean(axis=1)
df['result'] = df[2] * df['average']

print(df)

'''
     0    1   2   3  average  result
0  40   60   3   3     50.0   150.0
1  60   80   8  11     70.0   560.0
2  80  100  30  41     90.0  2700.0
'''
# ----------------------------------------------

data = [
    [40, 60, 3, 3],
    [60, 80, 8, 11],
    [80, 100, 30, 41]
]

for row in data:
    #d = [row[column] for column in [0,1]]
    d = row[0:2]
    average = sum(d)/len(d)
    print(row, d, average, row[2]*average)

'''
[40, 60, 3, 3] [40, 60] 50.0 150.0
[60, 80, 8, 11] [60, 80] 70.0 560.0
[80, 100, 30, 41] [80, 100] 90.0 2700.0
'''