10-4(2x+5)=6y-13
4y-63=5(4x-2y)+2
4y-63-20x+10y-2=0
14y-65-20x=0
x=0.7y-3.25
3-8x-6y=0
3-8*(0.7y-3.25)-6y=0
3-5.6y+26-6y=0
29-11.6y=0
y=29/11.6y=2.пятых
14*2.5-65-20x=0
-30-20x=0
x=-30/20
x=-1.5
D=b^2-4ac
D=(-13)^2-4*2*6
D=169-48
D=121
x1=b+√121/2*2=13+11/4=6
x2=b-√121/2*2=13-11/4=0,5