Answer:
b
Step-by-step explanation:
the question originally say 5x the 7th plus 7x to the eighth. The other is -(4x-2x). since there is a negative one in front of the expression u distribute it. it will be 5x to the 7th plus 7x to the eighth MINUS 4x to the 4th plus 2x to the eighth. You combine like terms....7x to the 8th and 2x to the eight....which is 9x to the eighth. you can't combine the others becuz the exponent are different and the bases too. So the answer is 9x to the 8th plus 5x to the 7th-4x to the 4th.
