Answer:
[tex]7[/tex]
Step-by-step explanation:
This means that there are 20 terms in between 11 and 31
[tex]31-11=20[/tex]
Since we know that the [tex]11th[/tex] term is [tex]29[/tex] and the [tex]31st[/tex] term is [tex]169[/tex], you can subtract the two to find out the values in between
[tex]169-29=140[/tex]
Now all we have to do is divide the values in between by the number of terms to find the common difference.
[tex]\frac{140}{20} =7[/tex]
Therefore the common difference is [tex]7[/tex]
