def sort_sum(row):
   return sum(row)

my_list = [[34, 51], [32, 15, 67], [12, 41], [54, 36, 22]]

print("The list is :")
print(my_list)

my_list.sort(key = sort_sum)

print("The result is :")
print(my_list)

The list is :
[[34, 51], [32, 15, 67], [12, 41], [54, 36, 22]]
The result is :
[[12, 41], [34, 51], [54, 36, 22], [32, 15, 67]]