Answer: Hello there!
We know that the pizza is divided into 16 slices; and that Elizabeth eats 1/8 of the pizza in 10 minutes:
First, let's see the number of slices that she eats in this 10 minutes:
1/8 of the pizza is equivalent to 2/16 ( if you multiply bot numerator and denominator by the same number). And knowing that the pizza is divided into 16 slices, we can see that she eats 2 slices in 10 minutes.
Now we want to know how many slices she can eat in one hour:
one hour has 60 minutes = 6*10 minutes (six times 10 minutes) then if she eats 2 slices every 10 minutes, she can eat 6*2 = 12 slices in one hour.
now, if we want to see how long will it take her to eat the entire pizza.
Again, we know that the whole pizza has 16 portions, and she eats 2 portions in 10 minutes, the ratio 16/2 = 8, says that she needs 8 times the amount of time to eat the whole pizza; this is 8*10 minutes = 80 minutes = one hour and 20 minutes.