This is the 761st most frequent Japanese word.
やすく
"やすく" means "cheaply" or "easily" (adverb form of やすい).
The word '安く' is used here as an adverb to describe the manner in which the clothes were bought, implying a low price.
この服は安く買えました。
I was able to buy these clothes cheaply.
The word '安く' is part of the construction '疲れやすく', modifying the verb to indicate susceptibility or tendency, in this case, to become tired.
最近、暑さで疲れやすくなりました。
Recently, due to the heat, I have become easily tired.
'安く' in '解決しやすく' conveys that the problem-solving process will become simpler or easier, showing potential for ease or facility.