Can someone explain how to do this: If you put 10 in to the function f(x) = 2x, what would be the output?

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Im so lost-

It would be 2 (10)

Step-by-step explanation:

If you replace x with 10 then you have a multiplacation problem  and the output of the answer is 20

System A: The lines overlap.

System B: The lines never intersect.

System C: The lines intersect at a point not on the y-axis.

System D: The lines intersect at the y-intercept.

Step-by-step explanation:

Got them right.