Answer:
<em>The greatest number of song he can practice in a week is 2.</em>
Step-by-step explanation:
Suppose, the greatest number of song he can practice in a week is 
He practices each song for
hours. So, the total time required for practicing
number of songs
hours.
Given that, he practices his guitar for 9 hours each week.
So, the equation will be......

<em>(Rounded as the greatest whole number)</em>
Thus, the greatest number of song he can practice in a week is 2.