Alright need answers 29-31 reply to this question that i posted

Write 5(6x+4)-2(5x-2) in the form a(bx+c) where a,b and c integers and a> 1

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?

Julie multiplies 6.27 by 7 and claims the product is 438.9 .explain without multiplying how you know juliesanswer is not correct.find the correct answer