His error is multiplying by 4 sides as he thought it was total surface not lateral surface area- the final answer is 12
Step-by-step explanation:
He should have multiplied it by 3, because the 3 sides- not including the base- is what lateral surface area is. He originally did total surface area not lateral surface area so each sides area is 4m squared then you just multiply it by 3 and its 12
