Answer:
I will give you the easy explanation here, go down there though to get a more complexed explanation and answer. Seeing it is a triangle, you can not multiply the 12 by 5. You have to multiply it by 2.5 because it dips in (because it's a triangle). Now you multiply the 5x5 to get 25. Now we have 25 for the base and 30 for each side. 30x4 to represent each side and add 25 for the base to get 145 as the final answer.
Step-by-step explanation:
Ok, they made this really easy with the 5's. You multiply the 5 by the 5 to get 25 in which the 12 there is about half of that, that made things really easy. Since the 12 goes to the middle that means that we can take what is from the middle to the side removing the half there getting you -2. Therefore, 12-2=10. Meaning the center is 10.
