There are an infinite number of answers to this question, when you include the negatives.
However, when just including the positive numbers, you have:
0 + 30
1 + 29
2 + 28
3 + 27
4 + 26
5 + 25
6 + 24
7 + 23
8 + 22
9 + 21
10 + 20
11 + 19
12 + 18
13 + 17
14 + 16
15 + 15
-30 plus 60 = 30
30 + 80 = 110
2+40+30=72
30 + 50 + 70 = 150
30
30
40+-30=10
150 plus 3 times 30 is equal to 240.
30 + 6
Yes.
Yes, 15 + 15 = 30
6 o'clock, probably.