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

sa = 2πr² + 2πrh
sa = 2π(5²) + 2π(5 x 1)
sa = 2π(25) + 2π(5)
sa = (2 x 25)π + (2 x 5)π
sa = 50π + 10π
sa = 60π

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.

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

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

a + 2x = 6a + 8x - 8
a = 6a + 8x - 8 - 2x
a - 6a = 8x - 8 - 2x
-5a = 6x - 8
a = \( \frac{6x - 8}{-5} \)
a = \( \frac{6x}{-5} \) + \( \frac{-8}{-5} \)
a = -1\(\frac{1}{5}\)x + 1\(\frac{3}{5}\)