Question 1042822
1 ft = 12 inches
15*1 ft = 15*12 inches
15 ft = 180 inches


The wall of "15 ft x 15 in x 3 in" is the same dimensions as the wall of "180 in x 15 in x 3 in"


Use the volume formula
V = L*W*H
V = 180*15*3
V = 8100


The volume of the wall is 8100 cubic inches


Here's where I can't keep going. I don't know how many cubic inches one bag can make. You'll have to look at each bag to determine this. That kind of information should be given. 


Let's say for example that each bag can make 100 cubic inches of concrete. That would mean you need 8100/100 = 81 bags. Replace "100" with whatever the bag states. If you get a decimal result, round up (not down) to the nearest whole number.