Answer :
remember to distribute invisible -1
(2+5x^4-5x)-1(7+6x+6x^2)
2+5x^4-5x-7-6x-6x^2
5x^4-6x^2-5x-6x+2-7
5x^4-6x^2-11x-5
(2+5x^4-5x)-1(7+6x+6x^2)
2+5x^4-5x-7-6x-6x^2
5x^4-6x^2-5x-6x+2-7
5x^4-6x^2-11x-5