Okay so if the pan is 12 inches wide you can divided 3 inches by that and get 4. Then do the same thing for the length, 18, and you get 6. Multiply 6 by 4 to get the number of brownies Pablo cut.
You can check my answer by drawing a box on a piece of paper, and drawing little boxes inside. Keep in mind that each brownie is 1 unit, or 3 inches.
