Normal distribution with a mean of 181.0 and a standard deviation of 57.0 find the percentage between 57.0 and 181.0 using 68 -95-99.7

Mean = 181.5
σ = 57
- σ = - 57

Between - σ and +σ the area (probability) = 68%, 
Due to symmetry we have:
The left are of the mean until - σ= the right area of the mean until + σ= 34%
Then the area (probability) from μ to +1 σ = 34%

1.17+3.99a. you combine the terms with a to create 3.99 and the 1.17 stays because it has no like terms or a variable