I need help i am so bad at math

Which formula finds the probability that a point on the grid below will be in the blue area? p(blue) = total number of squares number of blue squares number of blue squares p(blue) = total number of squares number of blue squares p(blue) = number of white squares

Using only the digits 5, 6, 7, 8, how many different three digit numbers can be formed if no digit is repeated in a number?

Find the amount of simple interest earned for depositing the given principle in an account if $2200 is invested at 5.5 % for 6 months