CREATE TABLE table_78851 ("Main contestant" TEXT, "Co-contestant  ( Yaar vs. Pyaar ) " TEXT, "Date performed" TEXT, "Scores by each individual judge" TEXT, "Total score/week" TEXT, "Position" TEXT, "Status" TEXT)

Who is the main contestant with a total score/week of 42/60 and a co-contestant (Yaar vs. Pyaa) of Tina Sachdev?
SELECT "Main contestant" FROM table_78851 WHERE "Total score/week" = '42/60' AND "Co-contestant (Yaar vs. Pyaar)" = 'tina sachdev'
SELECT "Main contestant" FROM "table_78851" WHERE "Co-contestant (Yaar vs. Pyaar)" = 'tina sachdev' AND "Total score/week" = '42/60'