Answer:
104
Step-by-step explanation:
It tells us the triangles are similar because of the ~.
The order matters in this statement: RST~RED.
It tells us which sides are proportional:
[tex]\frac{RS}{RE}=\frac{ST}{ED}=\frac{TR}{DR}[/tex]
So we are given DR=39 and ER=24 and RT=169.
Let's see which part of our equation we wrote that we can use.
Note: RT is same as TR. ER is same as RE.
We are using first and the last fraction of what I wrote:
[tex]\frac{SR}{ER}=\frac{RT}{RD}[/tex]
[tex]\frac{?}{24}=\frac{169}{39}[/tex]
To solve for ? just multiply both sides by 24:
[tex]?=\frac{169}{39}\cdot 24[/tex]
[tex]?=104[/tex]
