X) 7.2.17 find the values of x 20 and y 20 that maximize z 13x+ 15y, subject to each of the following sets of constraints. (a) x+ ys 19 (b) x 4y 2 20 4x y 2 16 x +5y s 35 (a) select the correct choice below and, if necessary, fill in the answer box to complete your choice. ? a. 0 b. the maximum value occurs at (type an ordered pair.) there is no maximum value. click to select and enter your answerfs) and then click check answer. part remaining clear all