Answer: There are 120 boats in the marina.
Step-by-step explanation:
Let's suppose that there are N boats
We know that 5/6 of them are white, then we have: (5/6)*N white boats.
The remaining is: N - (5/6)*N = (1/6)*N
We know that 2/5 of the remaining are blue, then we have:
(2/5)*(1/6)*N blue boats
And the rest are red, the rest is:
(1/6)*N - (2/5)*(1/6)*N = (3/5)*(1/6)*N
Then we have (3/5)*(1/6)*N red boats.
And we know that there are 12 red boats, then:
(3/5)*(1/6)*N = 12
Now we can solve this for N, which is the total number of boats in the marina.
N = 12*(6)*(5/3) = 120
There are 120 boats in the marina.