The answer in the book is 63105 thats all Why isnt 147 189

The answer in the book is {(6,3),(10,5)} .... thats all

Why isnt (14,7) , (18,9) etc... part of the answer?

Here are three sets: A={1, 2, 3, 4, 5, 6} , B={2, 4, 6, 8, 10} , C= {3, 5, 7, 9, 11). List the elements of the sets given by: {(x, y) | x=2y, x e B, y e C}

Solution

Condition is x=2y

Where x belongs to B and y belongs to C

And 6=2*3, 10=2*5

So there are only two such sets

And 14,18 etc doesnot belongs to B

Hence the answer is {(6,3),(10,5)}