could you please help me solve this simultaneous equation
$\displaystyle -3x+y=15
x=2-2y $
Just FYI Tex editor's don't recognize white space inside math tags so that is really hard to understand.
$\displaystyle -3x+y=15$
$\displaystyle x=2-2y $
subbing the 2nd equation into the first gives
$\displaystyle -3(2-2y)+y=15 \iff -6+6y+y=15 \iff 7y=21 \iff y =3$
Now sub in to find x $\displaystyle x=2-2(3)=-4 $ so the solution is
$\displaystyle (-4,3)$