Output the variables used in the following equation: y = 3x + 4
The variables used in the equation are 'x' and 'y'.
Below is an instruction that describes a task, write a response that appropriately completes the request.

### Instruction:
Output the variables used in the following equation: y = 3x + 4

### Response:
The variables used in the equation are 'x' and 'y'.