What is 2 gallons plus one cup plus 6 ounces

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

Evaluate this using ! 0.25^2 x 2.4 + 0.25 x 2.4^2 − 0.25 x 2.4 x 0.65

Sam opened a money-market account that pays 3% simple interest. he started the account with $7,000 and made no further deposits. when he closed the account, he had earned $420 in interest. how long did he keep his account open?