(m+x)-x = m+x-x = m
a-(a-b+2a) = a-a+b-2a = -a-b
4,5-(m-2m+0,5) = 4.5-m+2m-0.5 = 1.5+m
2,5+(13-15)-b = 2.5+13-15-b = 0.5-b
n-(m-n)-(2a+3b) = n-m+n-2a-3b = 2n-m-2a-3b
a-b+3b-(5a-7b) = a-2a+3b+7b = -a+10b
(m+x)-x = m+x-x = m
a-(a-b+2a) = a-a+b-2a = -a-b
4,5-(m-2m+0,5) = 4.5-m+2m-0.5 = 1.5+m
2,5+(13-15)-b = 2.5+13-15-b = 0.5-b
n-(m-n)-(2a+3b) = n-m+n-2a-3b = 2n-m-2a-3b
a-b+3b-(5a-7b) = a-2a+3b+7b = -a+10b