Question 136947
A cannot be done. that says -3 = +6
B {{{-2x + y = -3}}} and {{{y = -2x +7}}}
{{{-2x + (-2x +7) =  -3}}}
{{{-4x + 7 = -3}}}
{{{-4x = -10}}}
x = 2.5

C you have correct
D {{{2x+3y = -1}}} and {{{3x - 3y = -4}}}
{{{3y = -2x -1}}}
{{{3x - (-2x-1) = -4}}}
{{{5x + 1 = -4}}}
x = -1

You can solve for y :-D