What does the comprehensive cost rate of property insurance mean?

The comprehensive cost rate should be equal to A/D * A+B/D * B+C/D * C. It can also be seen from this formula that the comprehensive cost rate depends on two factors: one is the corresponding cost rate of each income, and the other is the proportion of each income in the total income ... Therefore, if we want to maximize the comprehensive cost rate, we only need to increase the proportion of the income with the largest cost rate ... for example.