Side ST correlates to side BC. Let's use these two sides to find the scale factor between the two triangles
[tex]\text{Scale Factor}=\dfrac{30}{40}=\dfrac{3}{4}[/tex]
Triangle ABC has side lengths are the 3/4 smaller than that of RTS. The value of x is the length of side AC, which correlates with side RS
Multiply 24 by 3/4 to find the value of x
[tex]x=\dfrac{3}{4}\times24=18[/tex]
This is answer choice C. Let me know if you need any clarifications, thanks!
