What do they mean by combining like terms?
When you combine like terms in an algebraic expression, you are combining expressions that have the same variables to the same power. For example, like terms would be 3x, -4x, and 7x because they have the same variable attached. Likewise, integers (4, 7, 45, -6) are considered like terms.
How do you find the percent of change?
The percent of change is usually solved by finding the difference between the values divided by the original value and multiplied by 100 (or new-original/ original * 100).
What is the difference of squares?
The difference of squares is when you have a binomial equation (a2 - b2), the simplified version is the square root of a and the square root of b in (a+b)(a-b)