Should I write the answer as decimal or a whole number

Maybe write the answer as a Decimal, sorry if that’s wrong ?

An easy way to solve this problem is to set up a proportion and cross-multiply. 

now cross-multiply, and you get this:

or 

so the actual car is 210 inches, but we need it in feet!
so 
the car is 17.5 feet in length!
Have a good day, and good luck with your homework.