Alex needs to varnish the top and bottom of a dozen rectangular wooden planks. The planks are 8 feet long and 3 feet wide. Each pint of varnish covers about 125 square feet and costs $3.50. What is the total area that Alex needs to varnish?

576 square feet.

Step-by-step explanation:

We have been given that Alex needs to varnish the top and bottom of a dozen rectangular wooden planks.The planks are 8 feet long and 3 feet wide.

We are asked to find the total area that Alex needs to varnish.

First of all, we will find area of one side of plank by multiplying the length and width o each plank as:  

The area for two sides of each plank would be 2 times 24 square feet that is .

The area for 2 sides of each plank is 48 square feet, so area of a dozen rectangular wooden planks would be 12 times 48 square feet.

Therefore, the total area that Alex needs would be 576 square feet.

since the airplane is moving with constant speed then the distance travelled can be calculated by x=u*t

in km/h would be:

x=640*3.5=2.240 km

in m/s would be:

u=640 km/h= 640.000 m/h =640.000/ 3600 m/s =177.8 m/s

t= 3.5 h= 3.5 * 3600 s=12.600 s

then x=u*t= 177.8*12.600= 2.240.280 m