Let the number of orders served by Mai, Abdul, and Chris be represented by M, A, and C respectively.
A total of 111 orders were served. Thus,
Abdul served 3 times as many orders as Chris. Thus,
Mai served 6 more orders than Chris. Thus,
Substitute equations 2 and 3 into equation 1. Thus, we have
Simplify by opening the brackets
Collect like terms, we have
Solve for C dividing both sides of the equation by the coefficient of C.
The coefficient of C is 5. Thus,
Solve for A by substituting the value of 21 for C in equation 2.
Solve for M by substituting the value of 21 for C in equation 3.
Hence,
number of orders served by Mai = 27
number of orders served by Abdul = 63
number of orders served by Chris = 21