In a school band, the ratio of the number of boys to the number of girls was $$5:3$$. After $$15$$ boys left the school band, the ratio of the remaining number of boys to the number of girls was $$5:6$$. What was the total number of pupils in the school band at first? 
Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Proportions->Ratio Word Problems with an Invariant Part