Order of operations

1. Evaluate expressions in parentheses
2. Evaluate exponents
3. Evaluate multiplications and divisions from left to right in the order that they appear
4. Evaluate additions and subtractions from left to right in the order that they appear.

In the absence of grouping symbols, addition holds no precedence over subtraction and vice versa.

15 - 8 + 4 = 7 + 4
					= 11

15 - 8 + 4 = 15 - 12
					 = 3