To find the average speed of the person during the entire journey, we need to first calculate the total distance covered and the total time taken.

Step 1: Calculate the distance covered in the first part of the journey.

The person drove at a speed of 53 kmph for 2.5 hours. The distance covered in this part can be calculated using the formula:

\(Distance = Speed \times Time\)

\(Distance_1 = 53 \, \text{kmph} \times 2.5 \, \text{hours} = 132.5 \, \text{km}\)

Step 2: Calculate the distance covered in the second part of the journey.

After the first part, the person increased the speed by 28 kmph. So, the new speed is:

\(53 \, \text{kmph} + 28 \, \text{kmph} = 81 \, \text{kmph}\)

The distance covered in the next 1 hour is:

\(Distance_2 = 81 \, \text{kmph} \times 1 \, \text{hour} = 81 \, \text{km}\)

Step 3: Calculate the total distance and total time.

Total distance covered is the sum of distances from both parts:

\(\text{Total Distance} = 132.5 \, \text{km} + 81 \, \text{km} = 213.5 \, \text{km}\)

Total time taken is the sum of times taken for both parts:

\(\text{Total Time} = 2.5 \, \text{hours} + 1 \, \text{hour} = 3.5 \, \text{hours}\)

Step 4: Calculate the average speed.

The average speed is given by:

\(\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} = \frac{213.5 \, \text{km}}{3.5 \, \text{hours}} = 61 \, \text{kmph}\)

Therefore, the average speed of the person during the entire journey is 61 kmph.