Concept:
Profit and loss problems involving variable counts of articles are solved most effectively by modeling the Cost Price (CP) of a single article as a constant variable or a specific nominal value. The relations governing profit and loss are:
• (Profit (Gain) = Selling Price (SP) - Cost Price (CP))
• (Gain Percentage = ( GainTotal Cost Price ) 100
Step 1: Setup the given algebraic equation.
Let the Cost Price of 1 article be denoted as (x).
Therefore, the total Cost Price of 50 articles is:
\[
\text{Total CP of 50 articles} = 50x
\]
According to the question statement, the Selling Price (SP) of 40 articles is exactly equal to the Cost Price of 50 articles. Thus, we have:
\[
\text{Total SP of 40 articles} = \text{Total CP of 50 articles} = 50x
\]
Step 2: Find the Selling Price of a single article to make an accurate baseline comparison.
Since the total Selling Price of 40 individual articles combined is (50x), the Selling Price of exactly 1 article is:
\[
\text{SP of 1 article} = \frac{50x}{40} = \frac{5}{4}x = 1.25x
\]
Step 3: Determine whether a gain or loss occurred, and compute its total financial value.
Comparing the cost price and selling price for 1 single article:
• (CP of 1 article = x)
• (SP of 1 article = 1.25x)
Since the Selling Price ((1.25x)) is strictly greater than the Cost Price ((x)), the transaction results in a Net Gain.
\[
\text{Gain on 1 article} = \text{SP} - \text{CP} = 1.25x - x = 0.25x
\]
Step 4: Compute the absolute Gain Percentage.
Using the percentage formula calculated against the base Cost Price:
\[
\text{Gain Percent} = \left( \frac{\text{Gain on 1 article}}{\text{CP of 1 article}} \right) \times 100
\]
\[
\text{Gain Percent} = \left( \frac{0.25x}{x} \right) \times 100
\]
Therefore, there is a total gain of 25