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).

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.

3a - 6 = \( \frac{a}{-8} \)
-8 x (3a - 6) = a
(-8 x 3a) + (-8 x -6) = a
-24a + 48 = a
-24a + 48 - a = 0
-24a - a = -48
-25a = -48
a = \( \frac{-48}{-25} \)
a = 1\(\frac{23}{25}\)

A trapezoid is a quadrilateral with one set of parallel sides.

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

sa = 2πr² + 2πrh
sa = 2π(3²) + 2π(3 x 6)
sa = 2π(9) + 2π(18)
sa = (2 x 9)π + (2 x 18)π
sa = 18π + 36π
sa = 54π

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 3 + 4 + 5 + 6
p = 18