Question 25438
{{{((j + 7) / b) + ((j - 9) / b)}}}
= {{{((j + 7) + (j - 9))/b}}}  ,since they have the same denominator b
= {{{(2j-2)/b}}}               ,since j + j = 2j and 7 - 9 = -2
= {{{2(j-1)/b}}}               ,factor 2 out