An expense item was $24\%$ of the total revenues in one year when the revenues were $$100,000.$ In the next year, the total revenues increased to $$120,000,$ and the same expense item was $20\%$ of the revenues. What type of cost would this be $-$ a fixed cost, a variable cost, or a mixed cost?

a fixed cost item

a variable cost item

a mixed cost item

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