Answer
$(-5/7, 16/7)$
Work Step by Step
We know that y=x+3. Thus, in the second equation, wherever we see y, we will substitute x+3, and then we will solve:
$ 3x+4(x+3)=7 \\\\ 7x+12 =7 \\\\ 7x=-5 \\\\ x=-\frac{5}{7}$
We now substitute x=-5/7 back in:
y=(-5/7)+3=$\frac{16}{7}$
We plug our values for x and y back into the first equation and confirm that our answer is, indeed, correct.
