Is it true that the order when dividing three real numbers does not effect the answer?

Jonah runs 3/5 miles on sunday and 7/10 mile on monday. he uses the model to find that he can ran a total of 1 mile . what mistake does jonah make

You buy 4 items that cost 2.69 14.45 8.05 13.95 what is the estimated total round to the nearest dollar

Which property was used to simplify the expression? 3c+9 +4c=3c+4c+9