1.已知m=2求16m+25-40m+34m 2.已知x=3求(4+2x)+(2x-x)3.已知a=1,b=3求4a+8a-(-6a)+3a-2b4.已知a=4求8a+4(a+2)5.已知n=3求(2n-3)+(2n+3)-(2n-3)6.已知x=1,y=-5求7x-(5x-5y)-y7.已知a=2,b=3求3a-4b+4a-3b8.已知a=4,b=5...