Can you help with this math question?

Question

In a large aquarium, there are many fish. There was a prime number of blue fish, and twice as many orange as blue fish. The sum of the yellow fish and striped fish was a multiple of 2, 3, 6, and 7, and twice the number of blue and orange fish combined. How many fish were in the aquarium?

Answer 1

orange = 2 x blue

O=2b

y+s = 2(O+b) = 2O+2b

y+s = a multiple of 2,3,6 & 7 = 252n where n= a natural number

O+b = 252n/2 = 126n

let n=1

O+b=126

2b+b =126

3b = 126

b = 42 blue fish

O= 84 orange fish

y+s = 252=2(84+42) = 252

total fish = 252+126 = 378 fish