Answer:
total cup = 32
1 student = 1/2 cup
find remaining cup = y
*we don't know how many students are there, so we just let it be x .
remaining cup = total cup - cup drank by students
y = 32 - 1/2x
y = -1/2x + 32 ( option c )
why 1/2x ? because we don't know how many students drank the juice, so we just let it be x .