Answer: [tex]s=\dfrac{(d-5)}{2}[/tex].
Step-by-step explanation:
Given: d denotes Diego's age while s denotes his sister's age.
The situation is represented by the equation d=2s+5.
To find his sister's age we can write the above equation as [tex]s=\dfrac{(d-5)}{2}[/tex] [we first subtract 5 from both sides and then divide both sides by 2]
Hence, the required equation: [tex]s=\dfrac{(d-5)}{2}[/tex].