Sagot :
so you add all the like terms.......i.e numbers with same variable
so,
5x+9y-7x+2-5y-7x+2-3x
=(5-7-7-3)x+(9-5)y+2+2
=-12x+4y+4
so,
5x+9y-7x+2-5y-7x+2-3x
=(5-7-7-3)x+(9-5)y+2+2
=-12x+4y+4