Question 294448
In general,
{{{an=a1+n*d}}}
Find a1 and d,
1.{{{a8=a1+8*d=76}}}

2.{{{a28=a1+28*d=96}}}
From eq. 1,
{{{a1=76-8*d}}}
Substitute into eq. 2,
{{{a1+28*d=96}}}
{{{(76-8*d)+28*d=96}}}
{{{76+20*d=96}}}
{{{20*d=20}}}
{{{d=1}}}
Then from eq. 1,
{{{a1=76-8*d}}}
{{{a1=76-8*1}}}
{{{a1=76-8}}}
{{{a1=68}}}
So then the rule becomes,
{{{an=68+1(n)}}}
{{{an=68+n}}}