The scale factor of ABC to DEF is the number you need to multiply a corresponding side of ABC to get one of DBC. We are given the two triangles are similar, so we can say that sides AB and DE are proportional. We are looking for the number we need to multiply AB by to get DE. From this relation, we can get the equation:
AB * x = DE
where x is our scale factor. We can substitute in the values of AB and DE, and solve for x:
5x = 15
x = 3
Therefore, the scale factor is three. This means that you can multiply any side of ABC by 3 to get a side of DEF.
