Final answer:
The correct equation to find out how many fewer students like red than purple after 2 students changed their vote from blue to red is 'Fewer students = students liking purple - 2', which is option (b).
Step-by-step explanation:
The question is asking how many fewer students like red than purple given that 2 students changed their vote from blue to red. To find out how many fewer students like red, we subtract the 2 additional red votes from the number of students who like purple. Therefore, the correct equation to determine how many fewer students like red than purple when 2 students changed their vote from blue to red is:
Fewer students = students liking purple - 2
This is represented by option (b). This equation basically starts with the number of students who prefer purple and subtracts the 2 students who shifted their preference to red, giving us the number by which purple is favored over red.