Let x be the certain number.
The sum of the certain number and 5 is equal to 15, so x + 5 = 15.
Subtracting 5 from both sides of the equation, we get x = 15 - 5 = <<15-5=10>>10.
Therefore, the certain number is 10. Answer: \boxed{10}.
If the product of 5 and the sum of a certain number is equal to 15, what is the number.
1 answer