Answer:

Step-by-step explanation:
Part (a) the probability that two people have a birthday on the 9th of any month.
Neglecting leap year, there are 365 days in a year.
There are 12 possible 9th in months that make a year calendar.
If two people have birthday on 9th; P(1st person) and P(2nd person).

Part (b) the probability that two people have a birthday on the same day of the same month
P(2 people selected have birthday on the same day of same month) + P(2 people selected not having birthday on same day of same month) = 1
P(2 people selected not having birthday on same day of same month):

P(2 people selected have birthday on the same day of same month) 
Equation = 12 - -24 = ?
After keep, change, flip: 12 + 24 = ?
Answer = 36
To solve this problem we can use simple proportion
If
270$ -------------------------3000 pesos
x $ ---------------------------100 pesos (x$ means that we dont know how much)
Now we crossmultiplying to get proportion
x*3000=270*100
Now we just to solve eq
3000x=27000 /:3000
x=27000:3000
x=9$ - its the result
If the solution of x is 3, then the solution of 6x would be 18, because 3*6=18. :)