You can replace u with -3 since u = -3. You should get something like this: -3 - 4(-3) + 3. This can be turned into -3 + 12 + 3, and subtracting negative numbers are the same as adding the positive version. -3 plus 12 is 9, and 9 plus 3 is 12. The final answer is 12. Hope this helps!
