Final answer:
The value of t is 65 seconds.
Step-by-step explanation:
To find the value of t, we need to determine the time it takes for Emily to walk to the post box. Since her speed is constant at 2 m/s, we can calculate the time using the formula: distance = speed × time.
From the graph, we can see that Emily walks a distance of 130 m to the post box and back. Since she walked to the post box at a constant speed, we can divide the total distance by her speed to find the time: t = distance / speed.
Therefore, t = 130 m / 2 m/s = 65 seconds.