An input-output table maps \(1,~2,~3,~\text{and}~4\) to \(2,~4,~6,~\text{and}~8\). Express how output \(y\) depends on input \(x\) as a symbolic rule.

The table describes the same operation from input to output in every row, and the requested rewrite must express that operation with x and y. Compare each output with its own input to decide whether the relationship uses a constant difference or factor, then translate the pattern into y equals an expression in x. Checking a middle row confirms the symbolic form did not change the relationship.