Respuesta :

It’s 678m2 because Given the dimension of a rectangular prism l×b×h,its surface area is 2(lb+bh+lh)Hence surface area of a rectangular prism that measures 12 m x 11 m x9 mis 2×(12×11+11×9+12×9)= 2×(132+99+108)= 2×339=678m2