URGENT VA ROGGGGGG MULT!!!!!

Răspuns:
1/6-1/7=(7-6)/6×7=1/7×6
S=1/6-1/7+17-1/8+1/8-1/9..+..+1/74-1/75=
S=1/6-1/75=(75-6)/6×75=69/6×75=
23/2×75=23/150