Answer:
x=a+b
Step-by-step explanation:
Just move a to the other side (by adding it)
Checking if the sequence is an arithmetic sequence
7 - 1 = 6
13 – 7 = 6
Therefore the sequence is arithmetic, with a_0 = 1 and d = 6
a_n = a_0 + (n-1)d
a_30 = 1 + (29)(6)
= 175
Therefore the 30th term is 175.