Find the surface area of one prism.
Two sides are 5 x 6 = 30 x 2 = 60 m^2
Two sides are 6 x 3 = 18 x 2 = 36 m^2
Two sides are 5 x 3 = 15 x 2 = 30 m^2
Total surface area = 60 + 36 +30 = 126 m^2
Now divide the total available by the total for 1:
1134 / 126 = 9
They can make 9 containers.