A cylinder is a solid figure with straight parallel sides and a circular or oval cross section with a radius (r) and a height (h). The volume of a cylinder is π r²h and the surface area is 2(π r²) + 2π rh.

Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).

The circumference of a circle is the distance around its perimeter and equals π (approx. 3.14159) x diameter: c = π d. The area of a circle is π x (radius)² : a = π r².

To solve this equation, isolate the variable for which you are solving (c) on one side of the equation and put everything else on the other side.

9c - 9x = -6c - 5x - 4
9c = -6c - 5x - 4 + 9x
9c + 6c = -5x - 4 + 9x
15c = 4x - 4
c = \( \frac{4x - 4}{15} \)
c = \( \frac{4x}{15} \) + \( \frac{-4}{15} \)
c = \(\frac{4}{15}\)x - \(\frac{4}{15}\)

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

4z + 3 = \( \frac{z}{-4} \)
-4 x (4z + 3) = z
(-4 x 4z) + (-4 x 3) = z
-16z - 12 = z
-16z - 12 - z = 0
-16z - z = 12
-17z = 12
z = \( \frac{12}{-17} \)
z = -\(\frac{12}{17}\)