Rozwiąż układ równań : a) x +y =22 y-2x=1 b) ×+y=100 ×-3=y +3

a) [latex] left { {{x+y=22} atop {y-2x=1}} ight. [/latex] [latex] left { {{x+y=22} atop {-2x+y=1}} ight. [/latex] [latex]x-(-2x)+y-y=22-1[/latex] [latex]3x=21[/latex] [latex]x=7[/latex] [latex]y-2x=1[/latex] [latex]y-14=1[/latex] [latex]y=15[/latex] [latex] left { {{y=15} atop {x=7}} ight. [/latex] b) [latex] left { {{x+y=100} atop {x-3=y+3}} ight.[/latex] [latex]left { {{x+y=100} atop {x-y=6}} ight.[/latex] [latex]x-x+y-(-y)=100-6 [/latex] [latex]2y=94[/latex] [latex]y=47[/latex] [latex]x+47=100[/latex] [latex]x=53[/latex] [latex] left { {{y=47} atop {x=53}} ight. [/latex]