What is the operation of "2.5y"

If f(x)=-x^2+6x-1 and g(x)=3x^2-4x-1,find(f+g)(x)

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.

Events a and b are independent. the probability of a occurring is 2/5. the probability of b occurring is 1/4. what is p(a and b)?