Write a function rule for "The output is 7 less than the input." Let x be the input and let y be the output.

x = y - 7

Step-by-step explanation:

The output is y and the input is x.

The information given says that output is 7 less than input, and since output is y and input is x, y is 7 less than x.

Since y is 7 less than x, you can put that into the form of an equation, which is how you get x = y - 7