I think you mean 2/5 and not 25 for Monday and 1/3 and not 13 on Tuesday. So i will solve with the fraction.
Answer: The fraction of the windows remaining for Kendra to wash=4/15
Explanation:
Step 1
The fraction of windows washed on Monday = 2/5
The fraction of windows washed on Tuesday= 1/3
Fraction remaining to be washed = Total windows - Fraction already washed
Step 255
Fraction already washed=2/5 + 1/3 =6+ 5/15 = 11/15
The total numbers of windows in the office will be represented as 1 whole number since we are dealing with fractions such that the
Fraction remaining to be washed = 1- Fraction already washed
= 1- 11/15 = 15/15-11/15= 4/15