If y varies jointly with x and y=5 when x=15 and z=24 find y when x=6 and z=14

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?

Can someone me with the property questions for 12 13 and 14 plz

Interpret the following expression (5y^2-7)^3/(2y)^2