Austin determined that he has $13.50 in his piggy bank just in quarters and dimes. If q represents the number of quarters he has and d represents the number of dimes, which equation, written in standard form, represents this scenario?

Each quarter is worth $0.25, so q quarters are worth 0.25q dollars. Each dime is worth $0.10, so d dimes are worth 0.10d dollars; together they total $13.50. Multiplying 0.25q + 0.10d = 13.50 by 20 gives 5q + 2d = 270, which is choice C.

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