The first month new members have to pay 188 dollars for the membership.
The equation is 160x+28=y
x stands for the number of months and y stands for the total cost.
For the first month (membership starts) the total cost is 188$. For the second month the total money paid would be 348$. For the third month the total money paid would be 508$. And so on you can use the equation to solve for more months. Just substitute x for the number of months you are solving for.
Because the two events are independent, their probabilities are multiplied, so the probability of a student being born in March and having a blood type of O+ is 9% * 40% = 0.09 * 0.40 = 0.036 = 3.6%