i dont understand.
The standard formula for an arithmetic sequence is
an = a1 + d (n – 1) where the term position is "n"
and the common difference is "d"
a50 = a1 + 6 • (50 – 1)
1001 = a1 + (300 – 6)
1001 = a1 + 294 ==> a1 = 1001 – 294
a1 = 707
a2 = 707 + 6
a2 = 713
.