5/8+(-3/5)+(-5/8)+5/3 what is the answer

Aline parallel to a triangle's side splits ab into lengths of x - 5 and x + 2. the other side, ac, is split into lengths of x and x + 12. what is the length of ac? a) 12 b) 24 c) 36 d)

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

Which of the following is the major negative aspect of crossover designs for research studies? a. prohibitive cost b. residual effects c-subject drepout d. incomplete randomization e. large sample size required