Answer:
semiannual 1.42%
yearly 2.85%
Step-by-step explanation:
Those are annual rate so we need to determinate the 6-month rate
The annual rate times the semiannual rate will be equal to the 18 months rate


r = 0.01416296 = 1.42%
If we want to express it annually:
1.0142^2 - 1 = r = 2.85%