You seem to be unaware of the fact that you could have obtained the answer much more easily and quickly by using the calculator that comes as part of your computer.
The answer is 42.
3 + 6 + 9 + 12 = 30
20 + 12 + 32 + 20 + 30 + 72 = 186
-6
61+24=85
The LCM of 12 and 30 is 60.
3 + 6 + m + 12 + 5 = 30 9 + m + 17 = 30 m + 26 = 30 m = 30 - 26 = 4
10 - 5 + 14324 + 12 + 30 - 1000 = 13371
16?
90+x+72+30 = 180. If you add 90+72+30, you get 192. But to get 180 you have to subtract 12. 90+(-12)+72+30 =180 if x is -12
4x+12-5x-30=-x-18
30 + 12 = 42, 12 + 12 = 24, I am not completely sure on the answer as the two subtractions can be taken in either order, either resulting in: 42 - 24 + 18, 18 - 12 = 6, or 24 - 12 = 12, 42 - 12 = 30.
18 + 24 - 30 = 12