Read this page. Order of operations agreement is a convention used by mathematicians to ensure that expressions with many operations are always evaluated the same way, which is consistent with the properties of operations. Because we are used to reading from left to right, it is natural to add and multiply in the same direction, instead of thinking which operations should be performed first. With practice, you will get used to the correct order and will read the expressions accordingly.
Work through examples A and B and Guided Practice problem 1. Complete practice problems 1-7. Make sure to watch the "Order of Operations" video embedded in the text.