aku minta tolong hitunglah deret ini !!! 1/42+1/56+1/72+........1/870

1/6×7 + 1/7×8 + ... +1/29×30=
(1/6-1/7) + (1/7-1/8) + ... + (1/29-1/30) =
1/6 - 1/30 = 4/ 30 = 2/15