An integer is chosen at random from the first 40 positive integers. what is the probability that the integer chosen is divisible by 6 or 8?

Well let's see how many numbers can be divisible by 6 or 8, add them up, and then put it into a fraction.
6: 6, 12, 18, 24, 30, 36.
6: 8, 16, 24, 32, 40.
Total: 
6, 8, 12, 16, 18, 24, 30, 32, 36, 40.
There are 10/40 positive numbers that can be divided by 6 or 8.
Simplified, 1/4.