Question 1056768
To solve, we first need to figure out the area of the trapezoid, and then multiply that answer by $0.60 per sq ft.  

Area of a trapezoid:
  {{{A = ((a+b)/2)h}}} 

Where
   a, b are the bases
  and    h  is the height

Note that a,b, and h are all given in the problem statement:
       a = 60
       b = 75
       h = 40

    A  = {{{((60+75)/2) * 40}}}
         = 2700 sqft

    C = cost of plywood = 2700 sqft * $0.60/sqft =  $1620