Answer: the answer is 11.836 and they are different because you have to add the improper fraction's to get the answer.
Step-by-step explanation:
First I added 5.815 and 6.021 which equals 11.836 then I made 5.815 into a mixed number which is 5 wholes and 815/1,000 and made 6.021 into a mixed number which is 6 wholes and 21/1,000 then added them which made it a improper fraction.
