Answer:
See Explanation
Step-by-step explanation:

(7 cm)*(10 cm) = 70 cm^2
The area is the product of length and width.
He is correct and incorrect. 2 and 4 can create factors but they can also be factors of other numbers. So 8 can be a factor of bigger whole numbers and can also have it own smaller factors.
to find the hypotenuse (or the ramp in question 4) you can use the equation

with a and b being the 3 feet and 9 feet and c being the unknown (ramp).
So if you plug 3 and 9 into the equation, it looks like this.

then square them.

simplify.

take the square root of both sides.

is approx. 9.5 so the answer would be H.