How to round 2.06 to the amount to the nearest dollar

If given an equation of a line such as -1/2x+6 how would you create an equation of a line parallel and perpendicula to this line that goes through another point such as (4,10)

Aconstruction worker has rope 9 m long he needs to cut it in pieces that are each 3 /5 m long how many such pieces can he cut without having any rope leftover?

8litres of paint can cover 129.6 m². how much paint is required to paint an area of 243m²?