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!