There are 3 warehouses A, B, C with a total of 546 boxes of face masks (all boxes are the same). The number of boxes from A, B, and C are 210, 189, 147 respectively. Three shops selling essential goods, P, Q, R, ordered 144, 129, 273 boxes of face masks respectively. The delivery costs (in RM) for each one box of face masks from a warehouse to a shop are summarized as follows.

P Q R

A 4.65 3.85 3.75

B 2.10 4.01 5.04

C 3.40 2.55 5.52

a)By using the Northwest-Steppingstone method, determine the manner which the boxes offace masks are to be delivered to the shops so that the total cost is minimum.

b)Determine such minimum cost.