# 2.11: Why It Matters- Calculations and Solving Equations

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## Why learn to complete calculations and solve equations?

Do you pay attention to the cost of a cup of coffee? Most people recognize that when they make coffee at home it’s cheaper than buying a cup of coffee that someone else has made. You’ve probably also noticed that some coffee places are more expensive than others—a cup of coffee at Starbucks usually costs more than one at a gas station, for instance. Regardless of where you decide to buy coffee, the price can change dramatically.

While retailers make decisions about how much they will mark up the coffee drinks they sell, the underlying coffee prices all around the world are driven by supply and demand. Coffee bean prices fluctuate for a variety of reasons and impact the final price you pay at your local coffee shop. The graph below shows the trading price of the coffee commodities index in Australia over the course of 40 years.

Coffee index prices in Austalia

If you own a bakery or another establishment that sells coffee, the data in this graph can be very useful. You can observe an overall historical trend and also relate political and environmental events to changes in that trend. If you need information about a specific year or a range of prices, you should be able to read this graph to gather that information.

As a retail professional, when you receive data specific to your store or product, it’s important that you can interpret the numbers so that you can make better decisions. Data will often be presented to you in the form of a graph, which is supposed to help readers visualize the information. Accounting information is initially documented in tables, but the outcomes can be presented in graphs to compare results over a desired time period. Tracking changes in profits, investments, customer spending, etc. is crucial in making decisions that will positively affect your business.