(Solved): Find the values of \( x \geq 0 \) and \( y \geq 0 \) that maximize \( z=13 x+15 y \), subject to ea ...

Find the values of \( x \geq 0 \) and \( y \geq 0 \) that maximize \( z=13 x+15 y \), subject to each of the following sets of constraints. (a) \( x+y \leq 15 \) (b) \( x+4 y \geq 20 \) \( x+2 y \leq 18 \) \( 4 x+y \geq 12 \) \( x-y \leq 14 \) (a) Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A. The maximum value occurs at (12,3) . (Type an ordered pair.) B. There is no maximum value. (b) Select the correct choice below and, if necessary, fill in the answer box to complete your choice. A. The maximum value occurs at (Type an ordered pair.) B. There is no maximum value.