Someone is answering the question.
Im not 100% sure but RT and US are the same distance so theyd be the same...
Answer:
b = 
Step-by-step explanation:
Given
a = 4b +
- b, that is
a = 3b + 
Multiply through by 3 to clear the fraction
3a = 9b + 2 ( subtract 2 from both sides )
3a - 2 = 9b ( divide both sides by 9 )
= b