What?

No I'm saying that to get from "80% of African Languages have no written form", to "Africans are illiterate", you have to assume that Africans only speak one language, and the unwritten languages are just as commonly spoken as the written ones.

One of my workmates is from Nigeria. He speaks five languages well enough to buy things in the shops and three fluently. I don't know if his local language or his tribal language have a written form, and looking at the numbers, I would guess not. But he's not illiterate. He reads and writes English with fluency, and can usually get the meaning reading French.

Having said that there is a lot of illiteracy in Africa, but nowhere near 80%. It's maybe a third, and it's driven by development, not availability of a suitable language that can be written.

The assumption that Africans are illiterate based on the lack of a written form for many African languages is flawed. My workmate from Nigeria speaks multiple languages fluently, though their local and tribal languages may not have a written form. Illiteracy in Africa is driven by development, not language availability.