Final answer:
Arun can text at a rate of 9 words per minute, so it will take him 20 minutes to text 180 words.
Step-by-step explanation:
If Arun can text 36 words in 4 minutes, we can calculate the rate at which he texts by doing the following:
First, divide the total number of words (36) by the number of minutes (4) to find how many words he can text per minute.
Which gives us 36 words / 4 minutes = 9 words per minute.
Next, to find out how long it will take him to text 180 words, divide the total number of words to be texted (180) by the number of words he can text per minute (9).
This calculation will be 180 words / 9 words per minute = 20 minutes.
Therefore, it will take Arun 20 minutes to text 180 words at the given rate.