I was wondering how やすい becomes やすく in 分かりやすくいえば?

Here is the full sentence:

> 分かりやすくいえば あいつらにとって葉山は友達で
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2020-05-24T11:10:13.493
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2020-05-24T11:57:35.173
2020-05-24T11:57:35.173
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question
grammar conjugations adjectives adverbs i-adjectives
Why does やすい conjugate to やすく in 分かりやすくいえば?
_i_ -adjectives like やすい turn into adverbs via the rule

> _-i_ → _-ku_

for example

  * やす **い** → やす **く**
  * 早 **い** → 早 **く**
  * 新し **い** → 新し **く**

The _i_ -adjective やすい can attach as a suffix to the _masu_ -stem of a verb
like 分かる, but the result 分かりやすい is grammatically still an _i_ -adjective and
in the phrase

> 分かりやすくいえば

分かりやす **く** is an adverb for the verb いう (here in the form いえば). (Similarly, 早
**く** いう "to say/speak quick **ly** " etc.)

Simple =)
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2020-05-24T11:56:09.297
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2020-05-24T11:56:09.297
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answer