Since 95 is the total number of comic books both boys have, it is equal to both boys' books added together. However, since we don't know how many books Kenny has, and only that he has 9 more than Bobbie, we can define that as (9 + b), or nine more than b. Then, we add b again, because (9 + b) is the number of books Kenny has, and if we add that to the number of books Bobbie has, it will equal the total of 95 comic books.
The main idea is the number of marbles and the denominator of the probability. All you have to do is multiply the fraction by a fraction which is equal to 1 which makes the denominator equal to 63. We know 63 is a multiple of 9. 9 goes 7 times in 63 so we multiple the fraction with which gives, which when evaluated gives and the numerator is the number of red marbles in the bag. So there are 14 red marbles in the bag :D