For parallel lines with a transversal, the following relationships apply:

• angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°)
• alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°)
• all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other
• same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°)

Applying these relationships starting with c° = 20, the value of b° is 160.

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 4 + 7 + 1 + 1
p = 13

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.

8y - 7 > \( \frac{y}{7} \)
7 x (8y - 7) > y
(7 x 8y) + (7 x -7) > y
56y - 49 > y
56y - 49 - y > 0
56y - y > 49
55y > 49
y > \( \frac{49}{55} \)
y > \(\frac{49}{55}\)

The volume of a cube is height x length x width:

v = h x l x w
v = 7 x 3 x 1
v = 21

The volume of a cylinder is πr²h:

v = πr²h
v = π(9² x 6)
v = 486π