multiply x times y divide by 6 on both sides and you got your answer
check the picture below, that's pretty much the same block, or "rectangular prism", with a width of 10, length of 5 and height of 1.
so anyhow, is really 6 rectangles stacked up to each other at the edges, so, we can simply get the area of each of those rectangles, add them up and that's the surface area.
front and back, two rectangles of 5x1
left and right, two rectangles of 1x10
top and bottom, two rectangles of 10x5

We have to find x and x is the hypotenuse. We use this formula:
hyp²=side²+side²
So:
hyp²=side²+side²
hyp²= 12²+9²
hyp²= 225
hyp²= √225
hyp= 15
Therefore, the hypotenuse is 15 and x is 15.
HOPE THIS HELPS!
HAVE A GR8 EVENING ;-)
14 is the answer sorry if I get it wrong :/
The answer is 78. This is because you change 8 2/3 into a improper fraction which is 26/3. Then do 26/3×9/1. You should cross cancel so cancel out 3 and change it into 1 and change 9 into 3. So now your problem is 26×3=78.
~JZ
Hope it helps.