Each bottle costs seven dollars. Two of them would cost $14 and three would cost $21. Buying three bottles, the amount is $21 which exceeds $16. Therefore, a $5 discount will be given. Subtracting $5 from the $21 will give $16. You have just enough amount to buy THREE bottles of olive oil.
Think of this as (1/5)x - 4 = -75, where x is the number that we are trying to figure out. To figure this out, we want to get x by itself, so we can go:
(1/5)x=-71
x=-71*5
x=-355
So your number is -355
2 16/99 as decimal should be:
2 + (16/99) = 2 +0.17 = 2.17