How do the 9s count-bys relate to the 10s count-bys in the next row?

In simplified exponential notation, the expression a^2•a^-3•a 1/a 0

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?

Atown has a population of 12000 and grows at 3.5% every year. what will be the population after 7 years, to the nearest whole number?