Create new table column summing data from multiple tables

Hi,

I want to sum values by unique ID, and then add another value from a different table to those sums (based on the same unique ID) to create a new column in a table or create a new measure. 

I'm not sure if it's possible to append queries to create a new table or if the better solution is DAX but, frankly, I'm new to both approaches so I'm not sure what options are available or which is the most elegant solution. 

Below are some tables representative of the scenario. The data is imported into the dataset. 

Table 1. 

Table 2.

Effectively, I want to:

1.  By unique ID, sum ValueB values to create ValueC
2. Add ValueC to ValueA to create NewValue

The objective is to create a new Field in Table 1 called NewValue such that Table 1 would look like:

Table 1.