The sum of the two digits is 15 and the difference between them is 3. What is the product of the digits?

Let the number be x and y.
Then, according to the question,
x + y = 15 ...(1)
x - y = 3 ...(ii)
on adding Eqs. (i) and (ii), we get
2x = 18
⇒ x = 9
On putting the value of in Eq. (i), we get
y = 6
∴ Product = xy = 54