Given:7x^8+8x^6-2x+9-(4x^8+3x^7+3)
Following PEDMAS rule: the order of calculations, expand Parentheses first.
Take care of the rule that the product of two unlike signs makes a negative sign.
The expression can be rewritten: 7x^8+8x^6-2x+9-4x^8-3x^7-3
Then, deal with Exponents of PEDMAS. Combine like terms rearranging all the terms
in the order of descending power of x, and constant terms last.
(7-4)x^8-3x^7+8x^6-2x+(9-3)
The answer is: 3x^8-3x^7+8x^6-2x+6