If A and B are independent, then
.
a.



b. I'm guessing the ? is supposed to stand for intersection. We can use DeMorgan's law for complements here:



c. DeMorgan's law can be used here too:



You can solve this by using "similar triangles".
In triangle ABC, we are looking for side AC which is x. Side AC is similar to side DF in triangle EDF.
You can solve for side x by picking two sides in triangle ABC and their corresponding sides in triangle EDF. This is what I mean:

Substitute for the values of AC, BC, DF and EF:


To solve for y, do the same thing. Pick two sides on triangle ABC and their corresponding sides in triangle DEF.

Substitute for the values and solve:


We have the value x to be 5.5 units and y to be 6 units.
I believe you only need to know one angle.
For example, if you know angle 1, you can calculate angle 3. Angle 2 = angle 3 and angle 4 = angle 1.
Also, Angle 5= angle 1 and so on...
Answer: 
<u>Step-by-step explanation:</u>
(1) (12, 18, 27, ...)
The common ratio is:

The equation is:


The equation is:

The answer would be 13.9 kg of gravel used per square meter