select difference of (8x2-3x3) - (2x2-5x3)
(8x2-3x3) - (2x2-5x3)= (16-9)-(4-15)=7-(-11)=7+11=18
(8x^2 - 3x^3) - (2x^2 - 5x^3)= 8x^2 - 3x^3 - 2x^2 + 5x^3.= 8x^2 - 2x^2 + 5x^3 - 3x^3. Simplify together like terms.= 6x^2 + 2x^3