what is the answer to 3 5/12 + 1 3/8? another question since i don’t have many points lol. what is 2 9/10 - 1 7/18? these are mixed numbers btw. please answer and thank you!

Kilgore trout creates a new scale to diagnose depression. however, his scale only assesses one symptom of depression while ignoring others. which of the following is his new scale most likely lacking? a) test-retest reliability b) discriminant validity c) criterion validity d) alternate-forms reliability e) content validity f) none of the above