Original sentence:

The job demands computer skills, math ability and with accounting background.

Correct Sentence:1. The job demands computer skills, math ability with accounting skills.

Original Sentence:
My sister in not only a talented musician, but she is also teach with great success.
Correct sentence:
2. My sister is not only a talented musician, she also teaches with great success.
Original sentence: Raking the leaves this morning more than 100 geese flew overhead.
Correct sentence: When raking the leaves this morning 100 geese flew over
Original sentence:
Follow the directions for writing the essay carefully
Correct sentence: Directions for writing the essay correctly as followed.

Your sentences are all wrong.

Please study this site.

http://www.chompchomp.com/terms/parallelstructure.htm

In sentence 2, who is raking the leaves?

My sister is a talented musician and she teaches with great success as well

Nope.

Please try again. You want a parallel with "talented musician".

Original Sentence: The job demands computer skills, math ability and with accounting background.

Corrected Sentence: The job requires computer skills, math ability, and an accounting background.

To correct this sentence, we need to make the list of requirements more parallel. To do this, we can rephrase it as "The job requires computer skills, math ability, and an accounting background." This way, each item in the list is stated in a similar format, making it more clear and grammatically correct.

Original Sentence: My sister in not only a talented musician, but she is also teach with great success.
Corrected Sentence: My sister is not only a talented musician, but she also teaches with great success.

To correct this sentence, we need to fix the subject-verb agreement and remove the unnecessary word "in". The corrected sentence should be "My sister is not only a talented musician, but she also teaches with great success." This way, the subject "my sister" agrees with the verb "teaches" and the sentence is clear and grammatically correct.

Original Sentence: Raking the leaves this morning more than 100 geese flew overhead.
Corrected Sentence: While raking the leaves this morning, I saw more than 100 geese fly overhead.

To correct this sentence, we need to clarify the subject and verb agreement and add the correct verb tense. The corrected sentence should be "While raking the leaves this morning, I saw more than 100 geese fly overhead." This way, the subject "I" matches the verb "saw" and the sentence is clear and grammatically correct.

Original Sentence: Follow the directions for writing the essay carefully.
Corrected Sentence: Follow the directions carefully when writing the essay.

To correct this sentence, we need to rephrase it to make the instructions and action more clear. The corrected sentence should be "Follow the directions carefully when writing the essay." This way, the action of writing the essay is connected to the instructions being followed, and the sentence is clear and grammatically correct.