Answer:
There are 84 total boats.
Explanation:
In order to find this, we first need to find the fraction which are red. We can do this by multiplying the whole by how many are not white.
1 * 1/4 = 1/4
Now we take that amount and multiply it by the amount that are not blue of the remaining.
1/4 * 3/7 = 3/28
Now that we have this, and we know this is 9 boats, we can divide 9 by this fraction and it will give us the total number of boats.
9 ÷ 3/28 = 84