In reply to:

In French the number 70 is said as “sixty and ten” (soixante et dix)
The number 80 is said as “four twenties” (quatre-vingts)

I had a Belgian friend tell me once that in Belgian French, they often use "septante" and "huitante" for "soixante et dix" and "quatre vingts" - I liked that idea a lot, it made counting in French much simpler.