Question

The expression (m-n)-(n-m) is equivalent to

a) 2m-2n
b) 2m
c) -2n
d) m-n

Answer 1

$(m-n)-(n-m)=m-n -(n-m)= m-n-n+m=(m+m)-n-n=2m-2n$

Answer 2

$(m-n)-(n-m)=m-n-n+m=2m-2n$

The answer: a)