Answer:
Time of driving of Maria = 1.8 hours
Step-by-step explanation:
Let a be time drove by Carlos and b be the time drove by Maria.
Carlos and Maria drove a total of 233 miles in 4.4 hours.
Total time = 4.4 hours
            a + b = 4.4 ------------------eqn 1
 Carlos drove the first part of the trip and averaged 55 miles per hour. Maria drove the remainder of the trip and averaged 50 miles per hour.    
     Speed of Carlos =   55 miles per hour
     Speed of Maria =   50 miles per hour       
Total distance = 233 miles
That is
               55 a + 50 b = 233----------------------eqn 2
eqn 1 x 50
               50 a + 50 b = 220---------------------------eqn 3
eqn 3 - eqn 2
              55 a + 50 b -    50 a - 50 b   = 233 - 220
                   5a = 13
                    a = 2.6
Substituting in eqn 1
                 2.6 + b = 4.4
                           b = 1.8
Time of driving of Maria = 1.8 hours