Comprehensive practice sheet featuring three columns of integer addition and subtraction problems for students to solve.

Here are the solutions for the "Adding and Subtracting Integers" worksheet. I have calculated each column from top to bottom.

Column 1:
* $-9 + 9 = 0$
* $-7 + 8 = 1$
* $-8 + (-7) = -15$
* $-10 - (-4) = -6$
* $-9 - (-10) = 1$
* $-7 - 9 = -16$
* $8 + (-3) = 5$
* $-4 + 8 = 4$
* $2 + 7 = 9$
* $10 + (-10) = 0$
* $-7 - (-2) = -5$
* $-9 - (-7) = -2$
* $1 + 10 = 11$
* $5 + 9 = 14$
* $-5 - 10 = -15$
* $-2 - 9 = -11$
* $10 - (-3) = 13$
* $-8 - 9 = -17$
* $10 + (-9) = 1$
* $-5 - (-8) = 3$
* $-3 - (-1) = -2$
* $1 - 9 = -8$
* $6 - (-3) = 9$
* $-8 - 10 = -18$
* $-6 + (-10) = -16$

Column 2:
* $-8 + (-1) = -9$
* $-5 - 4 = -9$
* $7 - 10 = -3$
* $-9 + (-3) = -12$
* $9 - (-8) = 17$
* $10 + 7 = 17$
* $6 + 7 = 13$
* $-3 + (-4) = -7$
* $-4 - (-3) = -1$
* $-7 - 4 = -11$
* $10 - 1 = 9$
* $1 - 5 = -4$
* $-7 + (-1) = -8$
* $8 - (-5) = 13$
* $-4 - (-6) = 2$
* $-7 - (-3) = -4$
* $9 - (-1) = 10$
* $-4 + 7 = 3$
* $3 + 3 = 6$
* $8 + 8 = 16$
* $5 - 6 = -1$
* $1 - 8 = -7$
* $9 + 5 = 14$
* $-6 + (-6) = -12$
* $-8 + (-2) = -10$

Column 3:
* $-2 + (-1) = -3$
* $4 - 9 = -5$
* $-8 - 6 = -14$
* $-6 + (-9) = -15$
* $-9 - 4 = -13$
* $-1 - (-7) = 6$
* $-4 - 10 = -14$
* $-1 + (-1) = -2$
* $3 + (-10) = -7$
* $-6 - (-2) = -4$
* $10 + (-8) = 2$
* $5 + 2 = 7$
* $2 + 8 = 10$
* $10 - 5 = 5$
* $3 + (-2) = 1$
* $1 - 2 = -1$
* $1 - 4 = -3$
* $-4 + 1 = -3$
* $2 - (-10) = 12$
* $5 + (-3) = 2$
* $6 + (-1) = 5$
* $3 + 8 = 11$
* $3 + 9 = 12$
* $-9 - 2 = -11$
* $8 + 4 = 12$

Final Answer:
See the calculated lists above for the complete solution key.