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:
5
Step-by-step explanation:
The coefficient is known as "the number in front of the letter,' so since 5 is in front of the x, 5 would be the leading coefficient, especially since the outcome would be 5x+881.
I would have to know the space of the two rectangular prisms to answer this correctly
<u>360</u>, It doesn't matter the individual side just the sum
100 x 4.2 would equal 420.
The answer is 4.2