a)
[tex]\left \{ {{3x+2y=1} \atop {x=-5+2y}} \right. \\3(-5+2y)+2y=1\\-15 +6y+2y=1\\8y=16\\y=2\\x=-5+2*2=-5+4=-1[/tex]
b)
[tex]\left \{ {{3x-y=2} \atop {x=3y-10}} \right. \\3(3y-10)-y=2\\9y-30-y=2\\8y=32\\y=4\\3x-4=2\\3x=6\\x=2[/tex]
