Question

please help I dont understand Scale factor ​

Answer 1

$\\ \sf\longmapsto \dfrac{x}{45}=\dfrac{18}{27}$

$\\ \sf\longmapsto \dfrac{x}{45}=\dfrac{2}{3}$

$\\ \sf\longmapsto 3x=90$

$\\ \sf\longmapsto x=\dfrac{90}{3}$

$\\ \sf\longmapsto x=30$