The surface area is the sum of all the sides of a shape. For a rectangle, we use
2(lw)+2(lw)+2(lw). NOTE: each value of l and w is going to be different. If we try to imagine a rectangular prism in our heads we know that there are 6 sides and each pair has the same dimensions, which is why we multiply the l and the w by 2.
Let's try putting each of our values into the formula.
2(6x2)+2(6x5)+2(2x5)
=2(12)+2(30)+2(10)
=24+60+20
=104cm²