How do you calculate displacement on a velocity vs time graph?

Hint: To get the answer for this question, first understand what velocity vs time graph is, then understand what all details can be gathered from the graph. After all the details about the graph is known, then calculating the displacement from the given velocity vs time graph becomes easy.

Complete solution:
The displacement can be calculated on a velocity vs time graph, by taking into consideration the area under the graph with their respective signs and then add them. The resultant area acquired is the value of displacement with sign. Sign represents the direction of motion.

Normally, the area above the time axis is considered as positive and the area below the time axis is considered as negative, but this depends on the type of question. If the detail regarding the area is explicitly mentioned in the question, then consider that or else the above details about the area can be considered.

Additional Information:
A velocity-time graph is a graph that shows how the velocity of an object changes with time.
Velocity-time graphs give information about the journey taken by an object. On a

velocity-time graph the velocity is plotted on the y-axis and the time is plotted on the x-axis.

A velocity-time graph can be used to calculate the acceleration of an object or the distance travelled by the object. The gradient of a velocity-time graph is the same as the acceleration. The area under the curve on a velocity-time graph is the distance travelled by an object.

Note:
Graph based questions are the easiest question and are also easy to solve. Just the details of what the graph is representing must be clear, as that will help to calculate the required value. Generally, the slope of the line, the area under the curve, etc. this type of values needs to be calculated to get the required result.