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)
11/12 as a fraction is 11/12; as a decimal it is ~ 0.9167
The answer to your question would be 4hr I think
Answer:
C) 37
Step-by-step explanation:
1/2(PQ)=RQ
2.5x+17=6x-11
17=3.5x-11
28=3.5x
x=8
RQ=6(8)-11
RQ=48-11
RQ=37
4(x-3)-(2x+5)=-3x-27
4*x - 4*3 - 2x - 5 = -3x - 27
4x - 12 - 2x - 5 = -3x - 27
2x - 17 = -3x - 27
2x + 3x = -27 + 17
5x = -10 / : 5
x = -2