EXPLANATION
We can build and fill the table by applying the procedure shown on the first example:
Items Store A Unit rate Store B Unit rate #of items needed Total
Soda filled filled filled $13
Chips 3.36/14= 0.24 2.64/12=0.22 2*2.64 $5.28
Hot dogs 6.24/12 = 0.52 4.24/8 = 0.53 2 *6.24 $12.48
Hot dogs buns 2.24/8 = 0.28 3.24/12 = 0.27 2 * 3.24 $6.48
Fruit cups 2.04/4 = 0.51 4.08/8 = 0.51 4*2.04 $8.16
Skittles 4.34/7 = 0.62 7.56/12 = 0.63 3* 4.34 $13.02
Glow Sticks 14.40/30 = 0.48 8.10/18= 0.45 1 * 14.40 $14.40
-----------
$72.82
With $72.82 we can get the amount needed for all the guests.