I have a calc quiz tomorrow and have a quick question on integration. When do I use U-Substitution as an integration method vs Partial Fractions? Are they the same thing? Can I use either or in any integration problem? For example, Can't this problem be done by both methods?

Cassie is traveling 675 miles today to visit her brother and his family. so far, she has stopped for gas three times. at the first stop, she put in 7.1 gallons of gas and paid $23.79. at her second stop, she put in 5.8 gallons of gas and paid $19.08. and, at the third stop, 6.6 gallons and paid $20.39. at which stop did casey pay the most for gas?

How do i do this? i don’t understand

Aubrey read 29 books and eli read 52 books what number is equal to the number of books aubrey read?