Who's good at DC circuits

The equivalent resistance of the circuit in
the figure is Req = 69.0 ohms.

l----------19ohms-------73ohms--l
l----73ohms------------19ohms--l
l-----R--------battery----switch---l

Find the value of R
Answer in units of ohms

Im assuming that R is internal resistance, with the 2 sections in series...

Req= (1/(19+73)+1/(19+73))^(-1/2)+R

Req-46=R
69-46=23

Since the 19 and 73 ohm resistors in each string are in series you can just add them

We end up with an equivalent circuit with R in series with 2 parallel 92 ohm resistors
Any time you put 2 identical resistors in parallel the resistance is just 1/2 one of the resistors = 46 ohms.

So the equivalent circuit is now just R is in series with a 46 ohm resistor

The resistance in a series circuit just adds so:

Req = R + 46
R= 69-46= 23 ohms