Function notation: If f(x) = 4 - x, for what input is the output 7?

[vaneriv06]

Im having a hard time understanding the concept of how the answer to this following question was -3,

Question:

If f(x) = 4-x, for what input is the output 7?:shock:
please someone help!

 

[stapel]

Im having a hard time understanding the concept of how the answer to this following question was -3,

Question: If f(x) = 4-x, for what input is the output 7?

What did you get when you plugged "7" in for "y" (or, in this case, the output "f(x)") and solved for the input value "x"?

Please show all of your steps. Thank you!

 

[Otis]

... having a hard time understanding the concept of how the answer [is] -3

Subtraction is the same thing as "adding the opposite". In other words, subtracting a number is the same as adding the opposite of that number.

Therefore, subtracting -3 is the same as adding 3.

4 - (-3) is the same as 4 + 3

Does this explanation help at all?