Answer:
Step-by-step explanation:
First, make a model. If you are doing the first row to the eighth row and add 4, the easiest way to solve the problem is to make a model.
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Now that we have a model, you see how I split it up into 12th's? Now, I can do 12x15=180. Next, we can add up the remaining X's. 72 X's are remaining. Lastly, you add 180 and 72 together. Which equals 252. Hope this helps you!!