[tex]c)\\\\\left \{ {{2x-2y=3} \atop {5x+3y=-\frac12 /*2}} \right. \\\left \{ {{2(x-y)=3 /:2} \atop {10x+6y=-1}} \right. \\\left \{ {{x-y=\frac32} \atop {10x+6y=-1}} \right. \\\left \{ {{x=\frac32+y} \atop {10(\frac32+y)+6y=-1}} \right. \\\left \{ {{x=\frac32+y} \atop {15+10y+6y=-1 /-15}} \right. \\\left \{ {{x=\frac32+y} \atop {16y=-16 /:16}} \right. \\\left \{ {{x=\frac32-1} \atop {y=-1}} \right. \\\left \{ {{x=\frac12} \atop {y=-1}} \right.[/tex]
[tex]b) \\\\\left \{ {{5y=10x+5 /:5} \atop {3x-4y=6}} \right. \\\left \{ {{y=2x+1} \atop {3x-4(2x+1)=6}} \right. \\\left \{ {{y=2x+1} \atop {3x-8x-4=6 /+4}} \right. \\\left \{ {{y=2x+1} \atop {-5x=10 /:(-5)}} \right. \\\left \{ {{y=2*(-2)+1} \atop {x=-2}} \right. \\\left \{ {{y=-4+1} \atop {x=-2}} \right. \\\left \{ {{y=-3} \atop {x=-2}} \right.[/tex]
[tex]e) \\\\\left \{ {{\frac12x-2y=8 /+2y /*2} \atop {2x+5y=6}} \right. \\\left \{ {{x=16+4y} \atop {2(16+4y)+5y=6}} \right. \\\left \{ {{x=16+4y} \atop {32+8y+5y=6 /-32}} \right. \\\left \{ {{x=16+4y} \atop {13y=-26 /:13}} \right. \\\left \{ {{x=16+4*(-2)} \atop {y=-2}} \right. \\\left \{ {{x=8} \atop {y=-2}} \right.[/tex]
[tex]f)\\\\\left \{ {{0.4x+0.3y=1.4} \atop {0.1x+3y=2.3}} \right. /*10\\\left \{ {{4x+3y=14} \atop {x+30y=23 /-30y}} \right. \\\left \{ {{4(23-30y)+3y=14} \atop {x=23-30y}} \right. \\\left \{ {{92-120y+3y=14 /-92} \atop {x=23-30y}} \right. \\\left \{ {{-117y=-78 /:(-117)} \atop {x=23-30y}} \right. \\\left \{ {{y=\frac23} \atop {x=23-30*\frac23}} \right. \\\left \{ {{y=\frac23} \atop {x=3}} \right.[/tex]
