The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

z² - 18z + 35 = -5z - 5
z² - 18z + 35 + 5 = -5z
z² - 18z + 5z + 40 = 0
z² - 13z + 40 = 0

Next, factor the quadratic equation:

z² - 13z + 40 = 0
(z - 5)(z - 8) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z - 5) or (z - 8) must equal zero:

If (z - 5) = 0, z must equal 5
If (z - 8) = 0, z must equal 8

So the solution is that z = 5 or 8

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

The formula for circumference is circle diameter x π. Circle diameter is 2 x radius:

c = πd
c = π(2 * r)
c = π(2 * 16)
c = 32π

To solve this equation, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

5c(c - x)
5(6)(6 - 5)
5(6)(1)
(30)(1)
30

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 7 x 4) + (2 x 4 x 2) + (2 x 7 x 2)
sa = (56) + (16) + (28)
sa = 100