Answer:
56kmn
Step-by-step explanation:
The slope of your line is the x-coefficient: 5.
The slope of a perpendicular line is the negative reciprocal of that: -1/5.
Answer:
SA=2lw+2lh+2hw
Step-by-step explanation:
Surface area is the sum of the areas of all faces (or surfaces) on a 3D shape. We can also label the length (l), width (w), and height (h) of the prism and use the formula, SA=2lw+2lh+2hw, to find the surface area.
The answer would be the first choice. 
Explanation: The reason for this is that the question was pretty much just asking what the area of the resulting two-dimensional cross section would be -the shape in gray- (which can be found by using the formula
. To add on, since the dimensions of the shape are already given (5 and 3) all you've to do is multiply: 3*5=15
That's how you get to the answer.