So what you can do is breaking it up into cases.
Case 1: 10 heads at least
there are a total of 12 flips so you should do 12c10 (combintorics), this is 66
so there are 66 ways for case 1
Case 2: 11 heads at least
12c11 is 12 so 12 ways for case 2
Case 3: 12 heads at least
12c12=1 so there is 1 way for case 3,
If you add them all up you get 79, (66+12+1=79)
