Combine each of the following sets of objective functions into a single weighted-sum objective of the specified maximize or minimize form, weighting individual objectives in the proportions indicated.

(a) min 3x1 + 5x2 - 2x3 + 19x4 max 17x2 - 28x4 min 34x2 + 34x3 Results form min, proportions 5:1:3.

(b) max 20x1 - 4x2 + 10x4 min 7x2 + 9x3 + 11x4 max 23x1 Results form max, proportions 3:1:1.