Answer:
As follows,
Step-by-step explanation:
1.ST=RN (Given)
2.ST=SI+IT (Given)
.RN=RU+UN (Given)
3. SI+IT=RU+UN (Transitive property, From 1 & 2)
SI+IT=IT+UN (Given, IT= RU)
4.SI+UN (Cancelling IT on both sides on 3)