Answer
$L=29n+545$
Work Step by Step
If $L$ is a linear function of n, then
$L=mn+b.$
Given (2, 603) and (5,690), we find m
$m=\displaystyle \frac{690-603}{5-2}=\frac{87}{3}=29$
So far, $L=29n+b$.
To find b, insert (n,L)=(2, 603) and solve for b
$603=29(2)+b$
$603=58+b\qquad/-58$
$545=b$
Thus,
$L=29n+545$
