-2x-7=-4x
-2x+4x=7
2x=7
x=3,5
10-4(2x+5)=6y-13
4y-63=5(4x-2y)+2
4y-63=5(4x-2y)+2
4y-63-20x+10y-2=0
14y-65-20x=0
x=0.7y-3.25
10-4(2x+5)=6y-13
3-8x-6y=0
3-8*(0.7y-3.25)-6y=0
3-5.6y+26-6y=0
29-11.6y=0
y=29/11.6
y=2.пятых
14y-65-20x=0
14*2.5-65-20x=0
-30-20x=0
x=-30/20
x=-1.5
-2х+4х=7
2х=7
х=7:2
х=3,5