A firm has 5 senior partners and 4 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (2 groups are considered different if at least one group member is different) Choose the correct option
A) 70  B) 75  C) 80  D) 85  E) 90
The total number of ways to form a group of 3 is 9803 = 84   The number of groups without a senior partner is 4803 = 4   The number of groups which include a senior partner is  84-4= 
<gadget id="calculator"> 84-4</gadget>
<output>80</output>
80   The answer is 80.
<result>C</result>
A firm has 5 senior partners and 4 junior partners. How many different groups of 3 partners can be formed in which at least one member of the group is a senior partner. (2 groups are considered different if at least one group member is different)