I don’t understand what your problem is? You can read, can’t you?
Google even pops up a box with the relevant information immediately. Here, let me help you if that’s too hard:
“The cost of completing the nascent fiber-optic network connecting the capital cities of Sub-Saharan Africa and the main submarine cables is modest at $316 million, based on a cost of around $27,000 per kilometer.”
And that’s just the top result. You can look up the per km cost of almost any cable system trivially.
Google even pops up a box with the relevant information immediately. Here, let me help you if that’s too hard:
“The cost of completing the nascent fiber-optic network connecting the capital cities of Sub-Saharan Africa and the main submarine cables is modest at $316 million, based on a cost of around $27,000 per kilometer.”
And that’s just the top result. You can look up the per km cost of almost any cable system trivially.