Answer:
a) 弦 -> 畜 -> 胃 -> 腕
弦 GEN, tsuru - string, bowstring
畜 CHIKU - animal raising, domestic animal
胃 I - stomach
腕 WAN, ude - arm, ability, talent, skill
b) 晩 -> 勉 -> 加 -> 吹
晩 BAN - evening, night
勉 BEN - effort, hard work
加 KA, kuwa(eru), kuwa(waru) - add, append, join, take part
吹 SUI, fu(ku) - blow