1.设十位上为a,个位上为b,a+b=n,所以所求为10a+b+10b+a=11n
2.设快车速度为x,慢车速度为y,则4(x+y)=184+168①
16(x-y)=184+168②,2个式子联立解出x=55,y=33
3.(6×8+8×7+9×5)/(6+8+9)=149/23
1.设十位上为a,个位上为b,a+b=n,所以所求为10a+b+10b+a=11n
2.设快车速度为x,慢车速度为y,则4(x+y)=184+168①
16(x-y)=184+168②,2个式子联立解出x=55,y=33
3.(6×8+8×7+9×5)/(6+8+9)=149/23