Sherry's Paycheck Was $1300.00. When She Cashed Her Check At The Bank, The Teller Gave Her A Total Of 25 Bills, Both Hundreds And Twenties. How Many Twenties Did The Teller Give Sherry?

Let t represent the number of 20s.
  20t + 100(25-t) = 1300
  -80t + 2500 = 1300
  -80t = -1200
  t = 1200/80 = 15
Sherry received 15 twenty-dollar bills.