After being marked up 40%, the sale price of a tennis racket is $87.50 What was the original price of the tennis racket?

$62.50

Step-by-step explanation:

The original price is x

It is marked up 40 percent

x+.40x = new price

1.40x = new price

The new price is 87.50

1.40x = 87.50

Divide each side by 1.40

1.40x/1.40 = 87.50/1.40

x =62.50

The price before mark up is 62.50

$62.50

Step-by-step explanation:

After mark up, price is

100 + 40 = 140% of cost

140/100 × Cost = 87.50

Cost = 87.50 × 100/140

Cost = $62.50

19.

step-by-step explanation:

you add the 9 in the tens column since it is a single digit and 9 plus zero is 9 so it is 19

if the eqn of the parabola is f(x) = (x-4)(x+2), we need to mult. this out to find the coordinates of the vertex.

then f(x) = x^2 + 2x - 4x - 8, and f(x) = x^2 - 2x - 8.

one way in which you can find the vertex is to calculate x = -b / (2a).   here, that comes to

        )

x = = 1.   f(1) = 1^2 - 2(1) - 8 = - 9.   vertex is at (1, -9).

        2(1) 

find another point on the curve:   let x=0, for which y=-8.   then (0, -8) is on the curve.   plot the vertex and this point and draw a smooth parabola thru both.

hope this