Directions: Study the table and answer the question that follows.

The table gives the total number of notebooks sold by five stationery counters on a particular day, along with the ratio of hardcover notebooks to softcover notebooks sold by each counter.

Stationery Counters	Total Notebooks Sold	Hardcover Notebooks : Softcover Notebooks
A	135	5:4
B	140	9:5
C	180	4:5
D	160	13:19
E	150	7:8

On the next day, counters A and C sell 20% and 25% more notebooks, respectively, than on the day shown in the table. If each counter keeps the same hardcover-to-softcover sales ratio, the number of hardcover notebooks sold by A is what percentage more or less than the number sold by C?

The correct answer is 10% less.

Step 1: Calculate the number of hardcover notebooks sold by Counter A on the next day.

From the given table, for Counter A on the first day:
• Total notebooks sold = 135
• Ratio of Hardcover notebooks to Softcover notebooks = 5 : 4

On the next day, Counter A sells 20% more notebooks than on the first day.

$\text{Total notebooks sold by A on the next day}=135\times \left(1+\frac{20}{100}\right)=135\times 1.20=162$

Since the ratio of hardcover to softcover notebooks remains 5 : 4, the total ratio parts are:

$5+4=9\text{ parts}$

Therefore, the number of hardcover notebooks sold by Counter A on the next day is:

$\text{Hardcover notebooks sold by A}=162\times \frac{5}{9}=18\times 5=90$

Step 2: Calculate the number of hardcover notebooks sold by Counter C on the next day.

From the table, for Counter C on the first day:
• Total notebooks sold = 180
• Ratio of Hardcover notebooks to Softcover notebooks = 4 : 5

On the next day, Counter C sells 25% more notebooks than on the first day.

$\text{Total notebooks sold by C on the next day}=180\times \left(1+\frac{25}{100}\right)=180\times 1.25=225$

Since the ratio of hardcover to softcover notebooks remains 4 : 5, the total ratio parts are:

$4+5=9\text{ parts}$

Therefore, the number of hardcover notebooks sold by Counter C on the next day is:

$\text{Hardcover notebooks sold by C}=225\times \frac{4}{9}=25\times 4=100$

Step 3: Determine the percentage difference between the hardcover sales of Counter A and Counter C.

We compare the hardcover sales of Counter A (90) relative to Counter C (100):

$\text{Difference}=100-90=10$

Since Counter A sold fewer hardcover notebooks than Counter C, we calculate the percentage less as:

$\text{Percentage less}=\left(\frac{100-90}{100}\right)\times 100\%=\frac{10}{100}\times 100\%=10\%$

Thus, the number of hardcover notebooks sold by Counter A is 10% less than the number sold by Counter C.