I need help with my Math 110 ?

Question

I do not know this and need help answering them.

Use the properties of real numbers and the properties of equality to prove each statement.

1). If -a=-b, then ac=bc.

2). If a-c=b-c, then a=b

Answer 1

2)   if a-c=b-c

         take -c at right hand sight

    

        a=b-c+c

        

           -c cancels the +c

    now we've a=b

Answer 2

1)- a = - b >> a = b

ac/c =bc/c >> a = b

ac = bc

2) a - c = b - c >>> a -c + c = b

a = b

Regards.

Answer 3

-a = -b

Multiply -c to both sides:

ac = bc

a - c = b - c

Add c to both sides:

a = b