(7x+1)(x-3)+20(x-1)(x+1)=3(3x-2)²+13

7x+1×x-3+20x-20×x+1=3×9x-4+13 7x+1x-3+20x-20x+1=27x-9 8x-3+1=27x-9 8x-27x=-3+1+9 -19x=7 x=-19:7 x=-2.71428571