Question 228582
Are of the floor: 15x20
                  = 300 sq.ft

For the first coat: 1 gallon covers 200 sq. ft so that would be one gallon.
Now 300-200= 100. We're left with 100 sq. ft. 1/2 gallon for that.
That makes 1.5 gallon for the first coat.

For the second coat: 1 gallon of varnish covers 300 square feet on the second coat so we only need 1 gallon.
 
Now we add both: 1.5+1=2.5 gallons required in total.