What is the vertex of (x) = –16x² + 64x + 80.

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?

How to do this , and can some one explain

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base