(6×3+2×2-4x)+(3×2-7x+1)+(2×3-5×2+8x-7)

Remove parentheses.

6×3+2×2-4x+3×2-7x+1+2×3-5×2+8x-7

Add 6×3 and 2×3.

8×3+2×2-4x+3×2-7x+1-5×2+8x-7

Add 2×2 and 3×2.

8×3+5×2-4x-7x+1-5×2+8x-7

Subtract 5×2 from 5×2.

8×3-4x-7x+1+0+8x-7

Add 8×3-4x-7x+1 and 0.

8×3-4x-7x+1+8x-7

8×3-4x-7x+1+8x-7

Subtract 7x from -4x.

8×3-11x+1+8x-7

Add -11x and 8x.

8×3-3x+1-7

Subtract 7 from 1.

8×3-3x-6

Add (6x^3+2x^2-4x)+(3x^2-7x+1)+(2x^3-5x^2+8x-7)