Упрости выражения. 1) a+2a+3b; 2) 4s+s+3r+s; 3) 3x+2y+x+5y;
1)a+2a+3b=3a+3b=3(a+b) 2)4s+s+3r+s=6s+3r=3(2s+r) 3)3x+2y+x+5y= 4x+7y