Subtract the difference
= 3 1/3 hrs - 1 3/4
convert mixed numbers to improper fractions
= 10/3 - 7/4
change to common denominator (12)
= 40/12 - 21/12
subtract numerators only
= (40-21)/12
= 19/12 or 1 7/12 hours as mixed #
ANSWER: It took 1 7/12 hours longer.
Hope this helps! :)