Answer:
RT = 20
Explanation:
Given S is at the midpoint of RT , then
RS = ST , that is
7y - 4 = 2y + 6 ( subtract 2y from both sides )
5y - 4 = 6 ( add 4 to both sides )
5y = 10 ( divide both sides by 5 )
y = 2
Then
RT = RS + ST = 7y - 4 + 2y + 6 = 9y + 2 = 9(2) + 2 = 18 + 2 = 20