(2.5y-4)(6y-1.8)=0
15y^2-4,5y-24y+7.2=0
15y^2-28,5y+7,2=0
D=812,25-432=380,25=19.5^2
x1=(4,5+19,5)\30=0,8
x2=(4,5-19,5)\30=-0,5