Jawaban:

Alright then.

1a. you see that y = 2x + 1 and 4x + y = 13.

all you need to do is to substitute the y in the latter equation with 2x + 1 since the former states so:

now we know that x = 2, how about y?

Moving on to b:

alright, so the question now does not directly show what x nor y is equal to, so we do it by ourselves. I am going to pick the first equation because it is easier:

Now we have our x by transposing all values to the right side. We will be using the second equation next:

Finally, the x: