If you scale something you basically multiply it by something. if you draw something at two times the scale, you are doubling it. so 9 ft would be scaled up to 18 foot. if you draw it at half the scale you cut it in half, so 9 would be 4.5.
The question is asking what do you multiply 9 feet by to get 6 cm. Now, it's not just 9 to 6, but feet to centimeters. A quick googling says the conversion is 1 foot = 30.48 centimeters. so 30.48*9 gets us 9 feet is 274.32 cm. So now we can simply find the scale factor between 274.32 cm to 6 cm. Since it is decreasing we know it is going to be less than 1. You basically use algebra though. what do you multiply 274.32 by to get to 6?
You can use linear equations if something is being raised or decreased with the same linear function. Such as temperature or the amount of books that get sold.
