Complementary angles sum upto 90°
so the complement of 9° = 81°
Answer:
The step 4 is not what he should have done. But the wrong is step 5, because if he added -2x both sides, it would give the following equation:

and not 
Note that in step 4 he should have added 2x and not -2x to both sides, but we still have the equality. The problem is that step 5 is totally wrong.
I don't know what answer is expected to this question, but I would mark step 5, because this is mathematically wrong.
Solving the equation

Using distribution

Add
both sides


Add 12 both sides

Divide both sides by 5

Answer:
<u>m</u><u> </u><u>is</u><u> </u><u>-</u><u>2</u><u> </u><u>and</u><u> </u><u>c</u><u> </u><u>is</u><u> </u><u>-</u><u>1</u>
Step-by-step explanation:
• Let's first phrase out the general equation of a line

- m is the slope
- c is the y-intercept
[ remember that a general line equation must be in slope - intercept form as shown above ]
• from our question, we are given the equation;

• let's make y the subject in order to make the equation in slope - intercept format.
→ <em>r</em><em>e</em><em>m</em><em>e</em><em>m</em><em>b</em><em>e</em><em>r</em><em> </em><em>t</em><em>o</em><em> </em><em>a</em><em>p</em><em>p</em><em>l</em><em>y</em><em> </em><em>"</em><em>s</em><em>u</em><em>b</em><em>j</em><em>e</em><em>c</em><em>t</em><em> </em><em>m</em><em>a</em><em>k</em><em>i</em><em>n</em><em>g</em><em> </em><em>k</em><em>n</em><em>o</em><em>w</em><em>l</em><em>e</em><em>d</em><em>g</em><em>e</em><em>"</em>

• The above boxed equation is now a general equation. Let's extract out slope, m and y-intercept, c

Answer:
Option C 
Step-by-step explanation:
we have

The compound inequality can be divided into two inequality
-----> inequality A
----> inequality B
Solve inequality A


Divide by -3 both sides
when you multiply or divide both sides of an inequality by a negative number, you must reverse the inequality symbol

Rewrite

The solution of the inequality A is the interval (-∞,-3]
Solve the inequality B


Divide by -3 both sides
when you multiply or divide both sides of an inequality by a negative number, you must reverse the inequality symbol

The solution of the inequality B is the interval [-6,∞)
The solution of the compound inequality is
[-6,∞) ∩ (-∞,-3]=(-6,-3]

180
This is because 12x5x3 = 180