Final answer:
The number the student is thinking of is 30.
Step-by-step explanation:
To find a number that is a multiple of 6 and 1 less than a multiple of 5, we need to find the least common multiple (LCM) of 6 and 5. The LCM is the smallest number that is divisible by both 6 and 5. In this case, the LCM of 6 and 5 is 30. So, the number the student is thinking of is 30.