Answer:
120 minutes
Step-by-step explanation:
Since it took him 240 minutes to study four subjects and it takes him an equal amount of time to study each subject, you can just divide 240 by 2
Another way to look at it is that the line for 2 subjects is in the direct center of both number lines, meaning you have to find half of the amount of time it took him to study 4 subjects since 4 subjects is at the end of the number line
