We are asked to determine the percentage of discount if the price for an item goes from $150 to $112.50. To do that we will use the following relationship:

Where "x" is the percentage of the discount.
Now we solve for "x" first by subtracting 150 from both sides:

Solving the operations:

Now we multiply both sides by 100:

Now we divide both sides by -150:

Solving the operations:

Therefore, the percentage of the discount is 25%.