Explanation:
an arithmetic progression or arithmetic sequence is a sequence of terms, where the difference bergen neighboring terms is a constant d for the whole sequence.
a1 = 29
a2 = 29 + d
a3 = a2 + d = a1 + d + d = 29 + 2d
...
an = 29 + (n-1)d
a7 = -13 = 29 + 6d
-42 = 6d
d = -42/6 = -7
therefore,
a10 = 29 + 9×-7 = 29 - 63 = -34