Final answer:
The original cost of the dress was $40, calculated by setting up the equation OP × 0.60 = $24 and solving for OP which equals $40.
Step-by-step explanation:
The student asked to find the original cost of a dress that Naomi bought for $24 at 60% of its original price.
To find the original price, we can set up the following equation: Original Price × 60% = $24.
We use the fact that the price Naomi paid is $24 which is 60% of the original price, so we express 60% as 0.60 in the equation.
The equation to find the original price (OP) is: OP × 0.60 = $24.
To find OP, we divide both sides by 0.60, giving us OP = $24 / 0.60, which simplifies to OP = $40.
Therefore, the original cost of the dress was $40.