Answer:

Step-by-step explanation:
The formula of a perimeter of a rectangle:

The formula of an area of a rectangle:

l - lenght
w - width
We have l = 3w and the perimeter P = 256 in. Substitute:
<em>divide both sides by 2</em>
<em>divide both sides by 4</em>

Calculate the area of a rectangle:

The triangle ABC is the half of the rectangle. Therefore the area of a triangle ABC is:

Answer:
C. There are infinitely many solutions.
Step-by-step explanation:
3x – 6 < 3x + 13
Subtract 3x from each side
-6 < -13
This inequality is always true.
There are infinitely many solutions.
Only one because there is one variable and the combined coefficients of x are non-zero.
(0.75(x+40)=0.70(x+20), 0.05x=14-30=-16, x=-320)