It is: (20+30)/2 = 25
30
25
It is 25
The number 30, itself, is a decimal number. So it is the nearest.There is no other "nearest" number. If there were, the number halfway between that number and 30 would be nearer to 30. And then the number halfway between that number and 30 would be nearer still. And so on.
It is 27.5, the number halfway between the two middle numbers.
The number halfway between two numbers is the average of those two numbers. In this case, the average of 30 and 60 is (30 + 60) / 2 = 45. So, the number halfway between 30 and 60 is 45.
Halfway between 30 and 80 is (30 + 80) ÷ 2 = 55.
32
It is: 30
50
It is: 48
15