She doesn't understand algebra therefore she will probably not pass the math final.

1. She doesn't understand algebra; therefore, she will probably not pass the math final.

2. She doesn't understand algebra, therefore; she will probably not pass the math final.

3. She doesn't understand algebra, therefore, she will probably not pass the math final.

(if yall think its the same, it isnt. Look carefully at the punctuation)

The correctly punctuated answer is 1.) She doesn't understand algebra; therefore, she will probably not pass the math final.

Explanation:

Punctuation is important to the structure of a proper sentence! In the first option we have a semicolon after algebra indicating a pause between two independent clauses. This basically mean both of these two statements could stand up fine as their own sentences, however work better together. In the second option, the semicolon is present after the "therefore" which doesn't make much sense really. Lastly, in the third option it's not present at all; this creates what we call a "run on sentence".

2. She doesn't understand algebra, therefore; she will probably not pass the math final.

Explanation:

This is the answer because if you look at the comma it is in the right place.