Question 475264
 the equations
(1) {{{ -x + y = 5 }}}
(2) {{{ x - y = 10 }}}
--------------
(1) {{{ y = x + 5 }}}
(2) {{{ y = x - 10 }}}
There is no solution to these equations
because they are parallel lines. In order to have a solution, 
they must intersect.
The coefficient of {{{x}}} is the slope, and it is {{{1}}} for both lines
--------------
--------------
(1) {{{ -3x + y = 5 }}}
(2) {{{ -6x + 2y = 10 }}}
There is no solution here because these are the same equation.
If you multiply both sides of (1) by {{{2}}}, you get the 2nd equation.