a) {5x-y=7 2(x+1)=2y b) 4(x-2)-y=1 2x-4y=8 c) {a/3+b/5=7 a/4-b/5=0 d) {k/3+l/4=1 k/4+l/8=1 e) {4p/9-5r/3=1 5/6 2p/3+2r/3=-0.1 f) {5x-5y=2.5 7y+3x=-14.5 g)20/y-12/x=1 10/y+8x=4 (c,d,g są to ułamki)

a) 5x-y=7 2(x+1)=2y 5x-y=7 (*-2) 2x-2y=-2 -10x+2y=-14 2x-2y=-2 -8x=-16(/-8) x=2 5x-y=7 10-y=7 -y=7-10 -y=-3 (*-1) y=3 b) 4(x-2)-y=1 2x-4y=8 4x-8-y=1 2x-4y=8 4x-y=9 2x-4y=8(*-2) 4x-y=9 -4x+8y=-16 7y=-7 y=-1 4x-y=9 4x=9-1 4x=8(/4) x=2 c) a/3 +b/5=7 (*3) a/4-b/5=0(*4) a+3b/5=21 (*5) a-4b/5=0 (*-5) 5a+3b=105 -5a+4B=0 7B=105 B=15 5a+3b=105 5a+45=105 5a=105-45 5a=60 (/5) a=12