Question 293220
The formula to use is
{{{(y - y[2])/(x - x[2]) = (y[1] - y[2])/(x[1] - x[2])}}}
where 
{{{x[1]}}},{{{y[1]}}} = (-4,0) and
{{{x[2]}}},{{{y[2]}}} = (0,1)
Plugging these values into the formula:
{{{(y - y[2])/(x - x[2]) = (y[1] - y[2])/(x[1] - x[2])}}}
{{{(y - 1)/(x - 0) = (0 - 1)/(-4 - 0)}}}
{{{(y - 1)/x = (-1)/(-4)}}}
{{{(y - 1)/x = 1/4}}}
Multiply both sides by {{{4x}}}
{{{4y - 4 = x}}}
{{{4y = x + 4}}}
{{{y = (1/4)*x + 1}}} answer
check:
does it pass through the given points?
(-4,0)
{{{0 = (1/4)*(-4) + 1}}}
{{{0 = -1 + 1}}}
{{{0 = 0}}}
and
(0,1)
{{{1 = (1/4)*0 + 1}}}
{{{1 = 0 + 1}}}
{{{1 = 1}}}
OK