Question 261879
To solve using substitution, we need to solve an equation for y. We already have that in the two given equations:
(i) {{{y=2x-3}}} 
(ii) {{{y=-x-3}}}
set them equal to get
(iii) {{{2x-3 = -x-3}}}
add x to both sides to get
(iv) {{{3x-3 = -3}}}
add 3 to both sides to get
(v) {{{3x = 0}}}
so, 
x = 0
and
y = -3