First let's review how to find the surface area of a rectangular prism. Since the opposite faces have the same area, we just need to find one of each pair of faces and multiply the result by 2.
One face in each pairs adds up to 6*4+2*4+2*6=24+8+12=44
Now we just need to multiply this by 2!
44*2=88 cm^2
I really hope my explanation helped, if there are any more question about this please ask me in the comments I will answer them.