First, we must define the two numbers using x. We already know that the greater number is x. However, the smaller number is half the greater number. This can be represented by 1/2x. Now, we can create a multiplication equation to find the value of x. This equation would be x(1/2x) = 450. This can then be simplified to 1/2x^2 = 450, then x^2 = 900. Finally, x = 30, or -30. Since the question is only asking for an expression, the answer would be x(1/2x) = 450.
Hope this helps!
