A scale factor is usually a decimal which scales, or multiplies, some quantity. In the equation y = Cx, C is the scale factor for x. C is also the coefficient of x, and may be called the constant of proportionality of y to x.
Since it's from a big square to a smaller square, the smaller number will be at the top. Also, use the same side to find the scale factor, but since this is a square and all sides of a square are equal, it doesn't matter but in other shapes it does so practice i guess:
