Answer:
6.78ft/sec
Step-by-step explanation:
From the question, dx/dt= 3.9 ft/sec
We are looking for Dy/dt
From geometry,vof this case the relationship between x and y is needed here, there is two similar triangle that exhibited by the man and the lamb
12/y= 5.1/(y-x)
Then ,cross multiply, we have
12(y-x)=5.1y
12y-12x=5.1y
12y-5.1y=12x
6.9y=12x
y=( 12/6.9)x
Differentiating implicitly the bother sides with respect to t, we have
Dy/dt= ( 12/6.9)dx/dt
But dx/dt= 3.9 ft/sec
Then Dy/dt= ( 12/6.9)× 3.9
Dy/dt=6.78ft/sec
Hence, the rate that the tip of the person's shadow moves away from the lamppost when the person is 9 ft away from the lampost is 6.78ft/sec
CHECK THE ATTACHMENT FOR THE FIQURE
15 is you answer sir. the multiples are 15,30,45,60,75<span>,90,105,120,135,150,165,180,195,210,225,240,255,270,285,300,315</span>
It's called the endpoint lol
Let x: the number of restaurants gift cards, and y: numbers of movie theaters gift card
50x+20y=450
x+y=15, so x=15-y
50(15-y)+20y=450
750-50y+20y=450
y=10
x=5.
As a result, Mr. Thompson buys 10 movie theaters give cards, and 5 restaurants gift cards. Hope it help!