It is (-15 + 20)/2 = 5/2 = 2.5
15
the answer is 15
The number 20 is.
17... and 19 !
The number is 15.
16
They are 16, 18 and 20.
35
(10+20)/2 = 30/2 = 15
The number half-way between is 15. 11, 12, 13, 14, 15, 16, 17, 18, 19 are all between 10 and 20.
10, 12, 14, 15, 16, 18, 20