(1)设原两位数为ab ab=10*a+b现在根据题意有方程:a+b=9 100*a+10*0+b=6*(10*a+b)联立解得:a= 1 ,b= 8 .(2)设山路X m,平地Y m。55min=11/12 h. 70min=7/6 h有方程:X/12+Y/9=11/12 X/6+Y/9=7/6解得:X=3 ,Y= 6 .