The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(9²) + 2π(9 x 1)
sa = 2π(81) + 2π(9)
sa = (2 x 81)π + (2 x 9)π
sa = 162π + 18π
sa = 180π

The area of a parallelogram is equal to its length x width:

a = l x w
a = a x b
a = 9 x 3
a = 27

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 < sign and the answer on the other.

-5y - 2 < 5 - 9y
-5y < 5 - 9y + 2
-5y + 9y < 5 + 2
4y < 7
y < \( \frac{7}{4} \)
y < 1\(\frac{3}{4}\)

A line on the coordinate grid can be defined by a slope-intercept equation: y = mx + b. For a given value of x, the value of y can be determined given the slope (m) and y-intercept (b) of the line. The slope of a line is change in y over change in x, \({\Delta y \over \Delta x}\), and the y-intercept is the y-coordinate where the line crosses the vertical y-axis.

A parallelogram is a quadrilateral with two sets of parallel sides. Opposite sides (a = c, b = d) and angles (red = red, blue = blue) are equal. The area of a parallelogram is base x height and the perimeter is the sum of the lengths of all sides (a + b + c + d).