subtract 5x+2x-11 from 3x+^2+8x-7
A = 3x² + 8x - 7 - (5x² + 2x - 11)A = 3x² + 8x - 7 - 5x² - 2x + 11A = 3x² - 5x² + 8x - 2x - 7 + 11A = - 2x² + 6x + 4