Answer:
Ty = √k * Tx
The orbital period of Y has to be be multiplied by √k . or . k∧1/2
Explanation:
The general equation:
T² = A³
is for the case of planet X
Tₓ² = Aₓ³
In the case of planet Y
Ty² = k * Aₓ³ . and Aₓ³ = Tₓ²
By substitution:
Ty² = k *Tₓ²
Ty = √k * Tx