Here is the item again:
Wendy pushed her glasses up her nose,
(A) and blew loose strands of
hair from her eyes, (B)
hoping that clearer vision would help her make sense of the difficult
algebra problem (C)
that she was trying to solve.
You correctly realized that the comma after nose was wrong. And blew loose strands of hair from her eyes is a lonely verb phrase. When you attach this type of phrase to the end of a main clause, you need no punctuation.
To fix the problem, you chose to do this:
Wendy pushed her glasses up her nose and
blew loose strands of hair from her eyes, hoping that clearer vision would
help her make sense of the difficult algebra problem that she was trying
to solve.
You have correctly employed Punctuation Rule 8:
Main clause + Ø + lonely verb phrase.
Great move!