Question

A scale model of a car is 10 inches long. the actual car is 15 ft long. What is the scale of the model?

Answer 1

Remember that the scale model is always SMALLER than the real thing. Never equal
So a fraction could help.
\[1 ft = 12 inches\]\[1 inch = 1/12 feet\]

To get the "scale of the model" both sides have to have the same unit
\[10 inches = 10 inches\] but \[15 feet = (15 \times12) inches\]
so in the end, we are comparing \[10 inches\] with \[180 inches\]
10 compared to 180 gives the "scale of the model" as 1:18