Question 1086752
Solve for n: 

S = n/2 (a + l) 

2S = n (2a + 2l) 

2S / 2 = 2an + 2ln / 2 

S = an + ln 

How do I continue?  Non-homework.
<pre>{{{S = (n/2)(a + L)}}} <===== l appears to be L, not 1, I guess
{{{S = n(a + L)/2}}}
n(a + L) = 2S ------ Cross-multiplying
{{{highlight_green(matrix(1,3, n, "=", 2S/(a + L)))}}}
IGNORE all other RIDICULOUS answers!!