Vincent gets a 100% on 3 out of every 5 Tests he takes. If Vincent takes 75 Tests this year, how may of them would he make a 100% on?

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 root of 9x plus 7 plus the square rot of 2x equall to 7