ab and ba are two numbers where a and b are co-prime. If the GCD of ab and ba are ( a + b ) /2 , then find the value of ( a + b ) .

Which statements describe postapocalyptic fiction? check all that apply. it considers humanity and survival. it shows the results of a disastrous event. it focuses on laws and theories of science. it occurs after the end of one world or society. it highlights the role of technology on humanity. it investigates the impact that historical disasters had on people.