To build a 2.5 m by 3 m deck...10 pts?

"to build a 2.5 m by 3 m deck, a local building supply store charges $1000 for materials, plus the carpenter's wage of $30/h. the store gives you an estimate of $1480 for the total cost. How much time is estimated for the carpenter to build the deck?" can someone please explain how i go about figuring this out?