$1.$ Arian borrowed a certain amount from his friend and promised to repay him, starting

in $1$ year from today, the amounts of $$1225,$ $$1350,$ $$1500,$ $$1600,$ and $$1600$ in $1$ to

$5$ years respectively. If the friend normally discounts investments at $8$ per cent p$.$a$.$

compounding monthly, how much did Arian borrow?