African Rift Valley?

Question

If the African Rift Valley opens up at a rate of 5 cm per year, how long will it take before a body of water 1000km wide divides the african continent? (please show work and how to do this!)

Answer 1

5 ONE HUNDREDTHS OF A METER PER YEAR EQUALS 1 METER IN 20 YEARS WHICH MEANS 20,000 YEARS FOR 1,000 METER WIDE RIFT TO FORM