how many of the positive factors of 14 are not factors of 21 ?
"factors of 14 - 1 , 2 , 7 , 14 , factors of 21 - 1 , 3 , 7 , 21 , comparing both , we have three factors of 14 which are not factors of 21 - 2,14 the answer is c"
divide(21, 14)