I will say its the correct answer
First we distribute

into

and

.


That makes the left side of the equation

Now we subtract

from

, which makes

Now the equation is

Our goal is to isolate

, so we both sides by 30
That will make the equation

We multiply -1 on both sides of the equation:

Finally we simplify

, which makes
So the answer is
Answer: the percent of the students at this university are foreign = 30%
Step-by-step explanation:
Given: Probability that college students are foreign students who also smoke: P(S|F)=0.12
Probability that foreign college students smoke P(S∩F)=0.4
The probability that the students at this university are foreign :
[By conditional probability formula]

Hence, the percent of the students at this university are foreign = 30%
2 km
4.5km - 2.5km = 2km. The 0.3m is negligible unless it means kilometers. If it is indeed kilometers, it is 1.7km.