Unsupported types for adding?

hey, so i have this code in:
sales_data = [[12, 17, 22], [2, 10, 3], [5, 12, 13]]
scoops_sold = 0

for location in sales_data:
for sale in sales_data:
scoops_sold += sale

however when i try to run it it says:
TypeError: unsupported operand type(s) for +=: ‘int’ and ‘list’
idk how to change the the type or what to do

iterate over the inner list…

for sale in location: