What does "IS" mean in an equation

Me because some of question i don’t understand

Divide. reduce the answer to lowest terms.5 2/3 ÷ 3 1/9

Sample response: if the graph passes the horizontaline test, then the function is one to one. functions that are one to one have inverses that a therefore, the inverse is a hinction compare your response to the sample response above. what did you include in your explanation? a reference to the horizontal-line test d a statement that the function is one-to-one the conclusion that the inverse is a function done