(2+5х)²-(3+5х)(5 х+3)=73
4+20х+25х²-15х+9+25х+15х=73
25х²+45х+13-73=0
25х²+45х-60=0 | :5
5х²+9х-12=0
Д=в²-4ас=81+240=321
Ну я хз