TeX source:

R C A_{j}^{k}=\left(\frac{X_{j}^{k}}{\sum_{k=1}^{K} X_{j}^{k}}\right) /\left(\frac{\sum_{i=1}^{G} X_{i}^{k}}{\sum_{k=1}^{K} \sum_{i}^{G} X_{i}^{k}}\right)