Clara has pennies and quarters in her purse. She counts a total of 28 coins. If the total value of the coins is 76 cents, which system of equations can be used to determine the number of pennies and the number of quarters? Assume p represents the number of pennies and q represents the number of quarters.
p + q = 28. p + 25 q = 76.
p + q = 28. 25 p + q = 76.
p + q = 76. p + 25 q = 28.
p + q = 76. 25 p + q = 28.