x+3x=-16; (2) 16y-2.5y-7.5y=5;
3x+5=4x+1; (4) 9-3y=5y+5.
3x=4x+3; (2) 6x-8=4x;
6y—7=4y—5;
①2x+2.7=24.7 ②x-x= ③