Question

what is -3.5 -(-2.8) i forgot!!!!

Answer 1

Subtracting a negative is the same thing as adding. :)
\[-3.5+2.8\]
You can rearrange it to
\[2.8-3.5\]
Your result should be a negative number.

Answer 2

I agree with @KamiBug when subtracting with a negative it would change to a positive....

\(\LARGE{\color{green}{-3.5-(-2.8)} \rightarrow {\color{red}{-3.5+2.8}}}\)