Answer:
a) 如 -> 吐 -> 城 -> 盛
如 JO, NYO - equal, like, as, as if
吐 TOU, ha(ku) - spew, vomit, give vent to
城 JOU, shiro - castle
盛 SEI, JOU, mo(ru), saka(n), saka(ru) - prosperous, energetic, serve food
b) 妙 -> 劣 -> 加 -> 味
妙 MYOU - strange, odd, adroit, mystery
劣 RETSU, oto(ru) - be inferior
加 KA, kuwa(eru), kuwa(waru) - add, append, join, take part
味 MI, aji , aji(wau) - taste