The youth center has another mural painted inside the building. if the original painting is 3 feet by 2 feet, and the mural is 15 by 10 feet, what is the scale comparing the painting to the mural?

The scale is determined by dividing the respective measures of the two paintings.

Original painting           mural       scale factor

3                                    15            original / mural = 3 / 15 = 1 / 5

2                                    10            original  / mural = 2 / 10 = 1 / 5

As you see the scale to comparing the original to the mural es   1 feet : 5 feet.  

It  means that the measures of the original painting must be multiplied by 5 to obtain the measures of the mural.