The number of species of coastal dune plants in Australia $2 E$ decreases as the latitude, in $^{\circ} \mathrm{S}$, increases. There are 34 species at $11^{\circ} \mathrm{S}$ and 26 species at $44^{\circ} \mathrm{S} .^{19}$
$3 i$
(a) Find a formula for the number, $N$, of species of coastal dune plants in Australia as a linear function of the latitude, $l$, in $^{\circ}$ S.
(b) Give units for and interpret the slope and the vertical intercept of this function.
(c) Graph this function between $l=11^{\circ} \mathrm{S}$ and $l=$ $44^{\circ} \mathrm{S} .$ (Australia lies entirely within these latitudes.)