Answer:
18
Step-by-step explanation:
This question is essentially asking what the greatest common factor of 72 and 90 is. The prime factorization of 72 is:
[tex]2^3\cdot 3^2[/tex]
For 90:
[tex]2\cdot 5\cdot 3^2[/tex]
Therefore, the greatest common factor is [tex]2\cdot 3^2=2\cdot 9=18[/tex]. Hope this helps!