We have the formula a+(n-1)d=nth term
Where a is the 1st term ,d is the difference and n is the nth term
So1st term= a
2nd term= (a+1)d
3rd term= (a+2)d
Adding ad+2d+ad+ 4d= 38
2ad+ 6d= 38
In the same way 7th term=(a+6)d
Adding these 2ad+15d=83
Subtracting, 9d= 45 which makes d=5
a+2d + a+4d=38 -->2a + 6d = 38
a+6d + a+9d = 83 --> 2a + 15d = 83
9d = 45
back in 2a+6d = 38
the sequence is:
4 9 14 19 24 ...
BTW, the definitions used by Praphul are not correct.
e.g. he said:
5th term is (a+4)d
that should have been a + 4d, the brackets there are critical
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