6x +3 = 6x -20 - x equations with variables

What is the vertex form of f(x) = x2 + 6x + 3

A) if $50000 is invested in a bank account that pays 9.3% of interest compounded on a six-monthly basis, how much money will be in the account after 3 and 12 years? b) if matusalen's father had put $2.0 in the bank when he was born and there, how long would matusalen have had to his death (969 years later) if the interest was 7% per year composed each month and weekly?

Lisa has three classes that each last 50 minutes. what is the total number of minutes of the three classes