What is the answer to this very hard question?

So we know that in all the seashells will be 40.

The ratio of ORANGE to PINK shells is 3:7.

Now we know that right now the sum is 10 seashells. To find the ratio of ORANGE to PINK seashells in a ration that has a sum of 40, we have to divide 40 seashells by 10 seashells (which is 4) and multiply it by both numbers (3 and 7). 

3:7 is equal to 3x4:7x4 > 12:28

Now we have to find how many orange seashells there are and we know that there are 12 orange seashells. :)

3:7 is 10 parts divide 40 by 10 = 4
Each part is 4
3*4 = 12      7*4 = 28
12:28
orange:pink

Ais the answer for your question