In a marble collection, 1/8 of the marbles are blue. of the blue marbles, 1/2 have sparkles. what fraction of the marbles in the collection are blue with sparkles?

Hello,i believe the answer is 3/8 of the  marbles in the collection are blue with sparkles.i say so  because if 1/8 of the marbles  are blue and of the blue marbles, 1/2 of them have sparkles, the remaining  of the marbles  must be blue with sparkles.  solution: 1/2 - 1/8 = 3/8thus, 3/8 of the  marbles in the collection are blue with sparkles.faith xoxo