- 21x ^ 5 - 21y ^ 5÷3x - 3y6y ^ 2 + 2× ^ 2 - 5xy×3× ^ 2 - 4y ^ 2 + 2xya + 3×a - 17× - 3×4 + 2×5a - 7b×a + 3ba ^ 2 + a + 1×a ^ 2 - a - 13× ^ 2y ^ 3 - 5a× ^ 4÷3× ^ 2a ^ 2 + 2a - 3÷a + 3× ^ 2 - 20 + ×÷× ?
- 21x ^ 5 - 21y ^ 5÷3x - 3y 6y ^ 2 + 2× ^ 2 - 5xy×3× ^ 2 - 4y ^ 2 + 2xy a + 3×a - 1 7× - 3×4 + 2× 5a - 7b×a + 3b a ^ 2 + a + 1×a ^ 2 - a - 1 3× ^ 2y ^ 3 - 5a× ^ 4÷3× ^ 2 a ^ 2 + 2a - 3÷a + 3 × ^ 2 - 20 + ×÷× + 5.