Problem 1
The relationship between the input and output is this:
output = 4*(input)
Meaning that whatever the input is, multiply it by 4 to get the output.
For example, if the input is 3, then the output is 4*3 = 12.
If you're wondering "why 4?" It's because squares have 4 equal sides, and we multiply the side length by 4 to get the perimeter or distance around the square.
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Problem 2
Let's replace "input" with x and "output" with y
That gives the equation y = 4*x or y = 4x. Both mean the same thing. Whenever we have a number next to a variable like this, it implies multiplication.