Probability(Subsets)

How many subsets of at least 4 elements does the set K={A,B,C,D,E,F,G} have ?
Please help me.I have the final exam tomorrow.

Thank you in advance

This is nothing to do with probability.
There are 7 elements in K.
Number of subsets of 4 elements is 7C4 = 35
Number of subsets of 5 elements is 7C5 = 21
Number with 6 elements is 7C6 = 7
Number with 7 elements is 1.

Total of these is 64, which is your answer.
If the big set K is omitted the answer is 63.