Add 7 with the diffrence of 12 and 9 =​

7+3 = 10

Step-by-step explanation:

if I understand the problem strangeness right, and there is nothing missing in it, then this is the simple answer.

the difference of 12 and 9 is 12-9 = 3.

and then adding this 3 to 7 is 7+3 =10

10

Step-by-step explanation:

The difference of 12 and 9 is 3.

Now,

If we add 7 to 3, the answer is 10.

students group

step-by-step explanation:

a person who   joins a party or a seminar can explain his feelings about that particular occasion better more than anyone else.

as bella managed a show for the students in the school and invited students to watch that show

hence

students group will be the best group to survey to find this information

the answer would be a 24

step-by-step explanation:

c=2πr=2·π·3=24