This math topic focuses on finding the length of a side of a partially shaded rectangle, given the total area of the rectangle and the area of the shaded part. It introduces students to logical reasoning with geometrical shapes, involving area calculation and proportion. The problems are structured to identify the relationship between the total and partial areas to determine the dimensions of subsets of shapes, reinforcing foundational concepts in area and perimeter calculations within practical contexts. This prepares students for more complex geometry and spatial reasoning tasks.