Question

How is the answer -1? How do I get it?

Answer 1

When distributing the negative three into the parentheses, that canceled out the -5 and made it a positive 15

Answer 2

5x- 3(x-5)=13

5x-3x+15=13

2x=-2

x is  -2

Your mistake is that you forgot to add when you multiply 3 and 5

and negative and negative make positive

hope this helps