Layla collects postcard. she has 7 postcards from europe .her postcards from europe are one third of her total collections. how many postcards in all does layla have

for this case we have by definition, if two lines are perpendicular, then the product of their slopes is -1.

then, given the following line:

so,

we are looking for m_ {2}:

then, the line is given by:

we find "b" replacing the given point:

finally, the equation is:

option c