You can approach this question in multiple ways, 2 of which are more obvious.
Method 1). Add up the number of marbles which aren't white divide that by the total number of marbles.
I.e. 8 + 14 + 10 = 32
32/48 = 2/3
[There are 48 marbles in total]
Method 2). Find the total number of marbles, divide the number of white marbles by the total (like method 1), then do 1 minus the answer.
I.e. 16/48 = number of white marbles
1 - 16/48 = 2/3
5 times 5..........................
