Sianna bought 3 pens, 4 notebooks, and a calculator. The calculator cost $25. If x represents the cost of each pen and y represents the cost of each notebook, which expression represents the amount of change Sianna should receive from $50?

The total cost is 3x for the pens, 4y for the notebooks, and $25 for the calculator, so it is 3x + 4y + 25. Change is the amount paid minus the total cost: 50 − (3x + 4y + 25). This matches choice C.

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