$$ 1st\ birthday\ deposit=\$ 500 $$

$$ 2nd\ birthday\ deposit=\$ 500+\$200=\$700 $$

Similarly deposit will be increased by $200 for every upcoming birthday. We have to find the deposits of all 6th birthdays.

$$ \therefore \ 6th \ birthday\ deposit=\$ 500+\$1000=\$1500 $$

And

$$ Total\ amount\ of\ money\ deposited=\frac{500+1500}{2}\times6=\$6000 $$