Simplifying each equation:

1) (x+5)+12=20
x + 5 + 12 = 20
x + 17 = 20
x = 20 - 17
x = 3

2) (30-) + 175 = 200
This equation seems to be incomplete or has a typo. Please provide the missing or correct information.

3) 15. + 133 = 17
This equation is incorrect. The sum of 15 and 133 cannot be equal to 17.

4) 14. + 54 = 82
This equation is incorrect. The sum of 14 and 54 cannot be equal to 82.

5) 15:(x+2) = 3
To solve this equation, we need to isolate x.
Multiply both sides of the equation by (x+2):
15 * (x+2) / (x+2) = 3 * (x+2) / (x+2)
15 = 3(x+2)
15 = 3x + 6
Subtract 6 from both sides:
15 - 6 = 3x + 6 - 6
9 = 3x
Divide both sides by 3:
9 / 3 = 3x / 3
3 = x

Therefore, the solution to the equation is x = 3.