Answer: A- $5,250
B- $7,750
Dolls = d
train = t
8d + 10t = 150
I think is let that
Lengthof train=X
platform length=180
total distance=x+180
speed=60km/hr=60×5/18=(300/18)m/
Time =18s
Time =Distance/speed
18=X+180/(300/18
18×300=18(X+180)
300=X+180
x=300-180=120
so length of the train=120m
Let P(x,y) be a point on the parabola. The definition of a parabola is the squared distance from P to focus F(2,2) equals the squared distance to the directrix x=8.
squared distance from P(x,y) to focus F(2,2)
(x - 2)² + (y - 2)²
squared distance from P(x,y) to the directrix x=8.
(x-8)²
Those are equal in a parabola,
(x - 2)² + (y - 2)² = (x-8)²
x² - 4x + 4 + y² - 4y + 4 = x² - 16x + 64
y² - 4y - 46 = -12x
That's a sideways parabola,
x = -(y² - 4y - 46)/12