Write an expression for the sequence of operations described below. add r to q, divide p by the result, then multiply 4 by what you have.

Can somebody me out with this question

Click on the graphic until you find the right quotient. (36xa - 30xb) ÷ (-6x2)

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?