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

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so

step-by-step explanation:

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let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.