Which of the following statements is not always true? a + (-b ) = -b + a

(a + b) + (-c) = a + [b + (-c)]

-(-a) = a

a - (-b) = (-b) -a

Step-by-step explanation:

The answer is a - (-b) = (-b) - a

for example if we take;

a = 4

b = 2

c = 2

and we replace;

4 - ( -2) = (-2) - 4

6 = -6

which is not true

All the remaining are true

even u can just use the values of abc and check if its true

answer: the first graph

step-by-step explanation:

it is contrapositive

i could not see the question too well so check yourself again too . this is because i want you to get it correct.