Answer:
The selling price would be $420.
Step-by-step explanation:
In order to find the mark up, we need to multiply the amount it originally costs by the percentage it is being marked up.
$300 * 40% = $120
Now that we have the mark up amount, we add it to the original cost to get the sale price.
$300 + $120 = $420
Answer:
4th option (sqrt(10))/2
Step-by-step explanation:

This is a parabola, first, locate the line of symmetry.
the line of symmetry is x=-b/2a
in this case, b=-2, a=-1, so the line of symmetry is x=-1
when x=-1, f(x)=-(-1)²-2(-1)-3=-2
locate the point (-1,-2) on the grid. this point is the vertex.
get two pairs of points with x=-1 as the symmetry line:
(0, -3) and (-2, -3); (1,-6) and (-3,-6)
connect these five points into a parabola, stick out at the ends because it will extend forever downward.