Kitchen is 20x15 = 300 sq ft
A. 10% more is 300 x 1.10 = 330 sq ft
B. Charge for installation will be ($6 + .36)300 + (tile cost * 1.06) = $ 5600
Remember..contractor BUYS 330 sqft but INSTALLS only 300 sq ft
solve for 'tile cost'
6.36(300) + 1.06 tilecost = 5600
1908 +1.06 tile cost = 5600
1.06 tile cost = 3692
tile cost = 3483.02 for 330 sq ft
sq ft tile cost = 3483.02/330 = $10.55 sq ft (again remember 330 sq ft purchased)