The scenario describes a situation of gerrymandering, where district boundaries are drawn in a way that gives one racial or political group an advantage over another. In this case, the demographic representation shows a majority of white voters (73% or 11 out of 15 squares) and a minority of black voters (27% or 4 out of 15 squares).
The encircled districts indicating the distribution of voters show that both districts are predominantly white (100% of the districts are white), which means there is no representation for black voters in Congress. Therefore, the likely effect on Congress would be that:
Congress reflects increased weighted favoring of one party despite rough parity in voter affiliation.
This is because gerrymandering can skew representation in a way that advantages one group (in this case, white voters) and limits the influence of the minority group (black voters).