You reverse the process of finding the second average, 21, which will help you find the original average, 25. First you multiply the second average, 21, to retrace your steps. We do this because the last thing we do when we find the average is divide. when you multiply 21 you get 42. Now you have the value of the first two numbers. Then you experiment with the numbers. To save time I'll get to the point. When you add 33 + 42 you get 75. Then you divide by 3 to get 25. You divide by three because the instructions say there was 3 numbers to start with. Hope this helps.
