Question

Suppose a plant grew 4 1/2 inches one week and 2 3/8 inches the next week. How many inches did it grow during both weeks?

Answer 1

7 inches if you round up for the fractions

Answer 2

41/2 + 2 3/8 can be written 4 4/8 + 2 3/8. We now have a common denominator.
Answer is 6 7/8.
Or convert everything to 1/8s

4 1/2 = 36/8    2 3/8 = 19/8   Both vulgar fractions
Add. 

36/8 + 19/8 = 55/8  Convert by dividing by 8
Answer = 6 7/8