If A(t) is the amount of salt in the tank at time t, then A(0) = 50 g and
A'(t) = (1 g/L)*(3 L/min) - (A(t)/120 g/L)*(3 L/min)

Multiply both sides by
, so that the left side can be condensed as the derivative of a product:


Integrate both sides and solve for A(t).


Given that A(0) = 50 g, we have

so that the amount of salt in the tank at time t is

The first term is 8, so 
Each time we want a new term, we add on 3
8+3 = 11
11+3 = 14
14+3 = 17
17+3 = 20
23+3 = 26
and so on
This recursive step of adding on 3 to the prior term is written as this:
which says "to get the nth term, add 3 to the term just before the nth term"
Based on what you posted for your answer choices, the final answer is likely choice C. However it seems some weird typo happened.
Answer:
MEEEE PLEASEEEEEEEE
Step-by-step explanation:
I think you have to multiply
Step-by-step explanation:

its 1/4 of the circle
circle circumference:

we need 1/4 of it, so its
