ANSWER
0.75
EXPLANATION
We have that the two triangles are equilateral, which implies they are similar.
To find the scale factor by which Triangle 1 was reduced to form Triangle 2, we have to divide the given length of Triangle 2 by that of Triangle 1.
That is:
[tex]\begin{gathered} \text{Scale Factor = }\frac{7.5}{10} \\ \text{Scale Factor = 0.75} \end{gathered}[/tex]
That is the factor.
