计算：
191919/767676 - 7676/1919
=19*10101/[76*10101]-76*101/[19*101]
=19/76-76/19
=1/4-4
=-15/4
26 88/97 ÷(-9)
=(27-9/97)/(-9)
=27/(-9)+(9/97)/9
=-3+1/97
=-2又96/97
1÷(1- 1/2 )÷(1- 1/3 )÷(1- 1/4 )÷…÷(1- 1/10 )
=1*2*3/2*4/3.*10/9
=1*10
=10