The answer is 100X because if you do 5x-4x first it will be 1x. Later on, if you do the exponent you have 1x times 1x. Then you do 1x+9x = 10x
Then you do 10x times 10x because of the exponent is telling you how times you do it and it equals to 100x.
Answer= 100x
I hope this helps YOU!
