What is the solution please? with steps

Question

A group of 7 females and 10 males volunteer for a medical study. How many selections of

seven volunteers have...

a.   

at least one male​?

   

b.   

at most one female​?

   

Answer 1

a) Total possible selections C (17,7)

Selections with only females C (7,7) = 1.

Selection with at least one male = C (17.7) - 1

b)

0 females C (10,7) ways

1 female C (10,6) x C (7,1) ways

Add these together