((1700+4x)*9):47-123=777
((1700+4х)*9):47-123=777 (1700*9+4х*9):47-123=777 (15300+36х):47-123=777 15300+36х=(777+123)*47 15300+36х=777*47+123*47 36х=36519+5781-15300 36х=42300-15300 36х=27000 х=2700:36 х=750