Concept:The question tests on the basics of framing equations and solving them.


M students received 3 sandwiches

->Every student received 3/m sandwich.

The fourth sandwich was shared b/w  (m-4) students.

Each student received  1 / (m-4) sandwich.


Carol has consumed the sandwich at both cases and hence she has consumed 


3/m   + 1/ (m-4)     [These fractions represent sandwich consumed by 1 student


=3(m-4) + m / m (m-4)


=3m -12 + m / m (m – 4)


4m - 12 / m (m-4) option (e)