Answer:
The answer is 4 whole 2 by 3 (4 2/3).
Step-by-step explanation:
(3/4) x = 3 1/2
3 x / 4 = 7/2
3 x = 14
x = 14/3 = 4 2/3.
I think the answer will be c
So we know that the bacteria grows 3x as much every ten minutes. From this we know that it'll be 3 mm in 20 minute. Continuing the pattern, we can figure out that in 40 minutes the bacteria will be 81 mm.
The pattern: 10min - 3 20min - 9 30min - 27 40min - 81
A formula is recursive if it expresses the term
in terms of the previous one(s) 
In this case, every term is 7 more than the previous one, so the formula for
will only involve
:

In fact, this formula is simply saying: for every index
, the term with that index is 7 more than the term before.
Also, we have to specify the starting point (otherwise we would go backwards indefinitely), so the complete recursive formula is

which means: start with 2 and generate every other term by adding 7 to the previous one.
Convert the percentage into a number then divide it by the income.