7 persons a, b, c, d, e, f and g are to be lined up in a row. If a, b, and c adhere always together, how many possible cases are there?  Choose the correct option:
A) 24 B) 36 C) 480 D) 720 E) 2880
firstly it is not GEOMETRY but COMBINATIONS, so changing the TAG accordingly..   total 7 are there..   take a,b, and c as one,so total =5..   these 5 can be arranged in 5! ways..   a,b, and c can be arranged within themselves in 3! ways ..   TOTAL = 5!*3!=720   720
<result>D</result>
7 persons a, b, c, d, e, f and g are to be lined up in a row. If a, b, and c adhere always together, how many possible cases are there?