If you have a 300 ohm transmission line terminated with an antenna that presents a (400 ohm - j 600 ohm) load impedance:

What is the normalized load admittance? (I come up with 1.5 - j 2 but am uncertain if correct)

How far from the load should a short circuit stub be placed to match the load? (can 0.25λ be correct?)

How long should the stub be? (can 0.085λ be correct?)

What is the VSWR before matching at the load?

What is the VSWR after matching at the input of the transmission line?