Why is there "the" in front of "dollars"? Does the meaning change if I skip the article "the" or say "a" instead of "the"?
The definite article "the" is used before dollars to make "dollars" a little bit more specific by referring to a particular amount of "dollars" that was earned by the airlines during this time. Since "dollars" is plural here, it would not be correct to use the indefinite article "a" before dollars. You could omit the definite article "the" here, however, it would make the sentence sound a little less natural.