Surface area is taking the area of each face and adding it together. The equation is 2lw + 2hw + 2hl. So, for example, you'd take the length and the width to the find the area of the top. Multiply this by 2 to find the top AND the bottom. You need to end with 6 sides and all these together to find your surface area.
Answer:
D.
or 
Step-by-step explanation:
The given equation is:

Divide through by 3;

Add the square of half the coefficient of x to both sides.


The left hand side is now a perfect square:

Take square root



D.
or 
Answer:
Area= base×height
Step-by-step explanation:
Answer:
1 because 91-18=1
Step-by-step explanation: