The Set B of all numbers y such that y is an even rational number. Define given set using set-builder notation.

Can someone answer this question for me

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?

Simplify the given expression leaving the answer in improper fraction form. 2/3+5/6