There are 3 ways of solving a simultaneous problem, substitution method, elimination method and Gauss-Jordan method. I'm gonna use the substitution method since it's easier and i think it would suit your level more.
First let's try solving for y since it's easier to start with.
Firstly we have to find an equation for x:

Great, now we can use the substitution method to find the value of y using the first equation:

Now we know that y=1 we can solve the first equation we made:

And the answer is 
Double check:

And that's our final answer! (4,1)
Answer:

Step-by-step explanation:
The formula ogf a volume of a pyramid:

B - area of a base
H - height
We have a base length a = 5 in and a height H = 9 in.
In the base we have a square. The formula of an area of a square is:

Substitute:

Calculate the volume:

Answer:
Angles BCF and EFH
Step-by-step explanation:
When two parallel lines are crossed by another line (the transversal), the angles in matching corners are called corresponding angles. DCF and GFC isn't the correct answer because those would be vertical angles. GFC and BCA would not be corresponding because they do not fall in matching corners. And same with EFH and BCA. Therefore, BCF and EFH would be corresponding.