I'm not going to answer the questions for you. Instead I will give you stuff taht will help you solve the problems.
A negative divided/multiplied by another negative will be positive
A negative divided/multiplied by a positive will be negative
Good luck with your math hw! If you need more help, just comment!
If each brick is within 1/8 inches of 8 inches, then that's an error of

If we then take the total length if each brick is 8 inches,

Then take 1/64 of this
![800*\frac{1}{64}=12.5[tex] So the upper and lower bounds are 12.5 inches either side of 800 inches 787.5, and 812.5 So we can say that [tex]787.5 \leq x \leq 812.5](https://tex.z-dn.net/?f=800%2A%5Cfrac%7B1%7D%7B64%7D%3D12.5%5Btex%5D%20So%20the%20upper%20and%20lower%20bounds%20are%2012.5%20inches%20either%20side%20of%20800%20inches%20787.5%2C%20and%20812.5%20So%20we%20can%20say%20that%20%5Btex%5D787.5%20%5Cleq%20x%20%5Cleq%20812.5)
Which would be the answer to part a. parts b and c would be the lower and upper bounds, so 787.5 and 812.5 respectively
Hope this helps
Number 1 would the last option, but I’m not sure about number 2