Solve for x just need to make sure i'm going in the right direction

This is solved in exactly the same way using exactly the same rule that was invoked in your other posting of a problem like this. (see link)

The product of near and far distances from the point of intersection of the secants to the circle is the same for both secants.

... 5×(5+x) = 6×(6+4)

... 5+x = 12 . . . . divide by 5

... x = 7 . . . . . . . subtract 5

to find the total number of combinations, multiply the quantity of each item by each other:

2 pairs of shoes x 3 pairs of shorts = 6 different combinations.