Помогите, кому не лень!!! Срочно

0.9x-4.5y=0.9(x-5y) 0.3х²-7.5y²=0.3(х²-25y²)= =0.3(x-5y)(x+5y) (0.9(x-5y))/0.3(x-5y)(x+5y)= =3/(x+5y)=3/4