A bag contains white marbles and red marbles, 25 in total. The number of white marbles is 8 less than 2 times the number of red marbles. How many white marbles are there?

14

Step-by-step explanation:

Let the number of white marbles be W and the number of red marbles be R, therefore, W + R = 25

and, W = 2R - 8

Using first equation, R = 25 - W and putting it in second, we get,

W = 2 (25 - W) - 8

W = 50 - 2W - 8

3W = 42

W = 14