why does the total amount of energy before and after any energy transformations remain the same?

Brief Explanations:

This is related to the law of conservation of energy. It states that energy cannot be created or destroyed, only transformed from one form to another. So, in any energy transformation, the total energy before and after remains the same as energy is just changing its form (e.g., mechanical to electrical, chemical to thermal etc.) but the overall quantity is conserved.

Answer:

Because of the law of conservation of energy which states that energy cannot be created or destroyed, only transformed from one form to another.