Is (3, 1) a solution to the equation y = 3x?

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

What is the interquartile range of this data set? 2, 5, 9, 11, 18, 30, 42, 48, 55, 73, 81

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?