<h3>
Answer:</h3>
-1
<h3>
Step-by-step explanation:</h3>
<u>We are given:</u>
a₁ = -17
a₁₃ = -29
<u>Solving for the Common Difference (d):</u>
We know that the formula for an AP is:
aₙ = a₁ + (n-1)d
The formula for the third term will be:
a₁₃ = a₁ + (13 - 1)d
<em>replacing the given values:</em>
-29 = -17 + (12)d
-12 = 12d [adding 17 on both sides]
d = -1 [dividing both sides by 12]
Hence, the common difference is -1
