Answer:
Finding averages.
Organizing data.
Estimating.
Data gathering.
Explanation:
When we plan an effective budget, we certainly need to gather some data about the theme, which includes, prices, description of the stuff we need. Once we have the data we need, then we must organize it to set priorities, to make the budget effective.
Additionally, estiamting and finding averages are important skills, because we need to estimate how effective is the budget. In fact, maybe we would desing different budgets to compare them and analyse, using averages, which one is the most effective.