There were n signers of the declaration of independence. the oldest was benjamin franklin, who was yy years old. 7 is 10% of yy and nn is 80% of yy. how many signers were there?

When you have 25 numbers, and jake picks 3 random numbers and puts them back, what is the chance bob has of picking those 3 numbers when he picks 6 random numbers (without putting them back)? explain.