Ateacher surveyed her class about their online accounts

Step-by-step explanation:

Thinking process:

Let the total set be the combination of all the sets as shown

It means that total items = 7 + 14 + 7 + 2

                                         = 30

But the total number of the subsets = 5 + 7+ 2

                                                            = 14

Therefore the probability  =

                                            =

                                            =

-2

7 - 9 = -2

reversed:

-2 + 9 = 7