3. if a customer buys 20 2 * 4's 8ft long, at $4.75 each, how much would the 2 * 4's cost? 2. [quote=raheel101;185090]1.How many 4' * 8' sheets of drywall do you need for the walls of a 12' * 20' room, 8ft high? See here, Area of four walls (on which you need dry-walls)$\displaystyle = 2\times (12 + 20) \times 8= 512 \;ft^2$Area of one sheet of dry-wall$\displaystyle = 4 \times 8 = 32 \;ft^2$Number of drywalls$\displaystyle = \frac {512}{32}= 16$3. 2.If ceramic tiles are 8'' * 8'', how manyu tiles would it take to cover an area 4' * 6'? See here, Area to be covered$\displaystyle = 4 \times 6 = 24 \;ft^2= 24\times 144 \;in^2 = 3456\;in^2$Area of one tile$\displaystyle = 8 \times 8= 64 \;in^2$Number of tiles$\displaystyle = \frac{3456}{64}=54\$