Question 115826

a)  
{{{x-y=8}}}
{{{x-y=-2}}}


*[invoke linear_substitution "x", "y", 1, -1, 8, 1, -1, -2]


b)  
{{{2x+y=5}}}
   {{{4x-3y=15}}}

*[invoke linear_substitution "x", "y", 2, 1, 5, 4, -3, 15]