(x+15)2,6+x(2,6)=455
2,6х+39+2,6х=455 5,2х=416 х=80
(Х+15)*2,6+х*(2,6)=455 2,6х+39+2,6х=455 5,2х+39=455 5,2=455-39 5,2х=416 Х=416:5,2 Х=80