There are 6 different singers who each sing two songs out of a set of 12 different songs. this month singer a sings songs 1 and 2, b sings 3 and 4, c sings 5 and 6, d sings 7 and 8, e sings 9 and 10, and singer f sings songs 11 and 12.find the number of possible assignments next month of two songs to various singers (so that all songs are sung)in which each singer sings at least one different song from the two songs he/she sang this month.