Question

1. Suppose a and b are real numbers where a > 0 and b < 0.

a. Is –a + b positive or negative. Explain how you know.
b. Is a – b positive or negative? Explain how you know.
c. Is b – a positive or negative. Explain how you know.

Answer 1

For a), use this chain of statements:
b<0<a
-a<0<-b
-a+b<b<-b+b
You can do something similar to b), and c) is just a) in disguise.

Answer 2

I still don't understand @blockcolder