3. the length of a living room is 12 feet and its width is 10.5 feet. the length of the room is being
expanded by x feet. write an expression to represent the new area of the living room in
square feet. you do not need to include the unit of square feet, just write the expression. feel
free to sketch out a rectangular room and label the given measurements to you visualize.
i need it before tomorrow

Since you're adding x feet to the length which is 12 feet:

New area: (12+x)10.5

Step-by-step explanation:

I am not sure I fully understand what your teacher wants from you, but I would say we only need to define the burning rate per hour for both people, and with that normed rate (number / hour) we can answer the main question directly.

Thomas burned 675 cal/ 2 hours.

by dividing to and bottom by 2 (it is important to do the same action on the top and the bottom to keep the value of the ratio unchanged) we get

337.5 cal / hour

and Marvin burned 1035 cal / 3 hours.

so, the same trick, this time dividing to and bottom by 3 to norm the whole ratio to a 1 hour baseline :

345 cal / hour

so, Marvin burned more calories per hour.