PLEASE HELP ASAP!!!
On a movie set, an archway is modeled by the equation
y = -0.5x2 + 3x, where y is the height in feet and x is the horizontal distance in feet. A laser is directed at the archway at an angle modeled by the equation -0.5x + 2.42y = 7.65 such that the beam crosses the archway at points A and B. At what height from the ground are the points A and B?

Question

PLEASE HELP ASAP!!!
On a movie set, an archway is modeled by the equation
y = -0.5x2 + 3x, where y is the height in feet and x is the horizontal distance in feet. A laser is directed at the archway at an angle modeled by the equation -0.5x + 2.42y = 7.65 such that the beam crosses the archway at points A and B. At what height from the ground are the points A and B?

anonymous · Answer

@jigglypuff314

jigglypuff314 · Answer

solve for y from -0.5x + 2.42y = 7.65
then y = y

anonymous · Answer

I dont understand

jigglypuff314 · Answer

solve for y from -0.5x + 2.42y = 7.65
what do you get?

anonymous · Answer

1y=0.21x+3.16

jigglypuff314 · Answer

yes
then since y = y
-0.5x^2 + 3x = 0.21x+3.16

anonymous · Answer

the choices are:
a:1.5ft, 3.5 ft
b:1.5 ft, 4 ft.
c: 3.5ft, 4 ft
d: 4 ft, 4 ft

anonymous · Answer

Do you know what the answer is?

jigglypuff314 · Answer

-0.5x^2 + 3x = 0.21x+3.16
           -0.21x    -0.21x
-0.5x^2 + 2.79x - 3.16 = 0   solve for x...
I suppose you can use the quadratic thing or wolframalpha.com

anonymous · Answer

x=4

anonymous · Answer

What do i do next?

jigglypuff314 · Answer

there are supposed to be two answers

anonymous · Answer

yeah. 
the x and the y

anonymous · Answer

I posted the answer choices. I dont know which one to choose

jigglypuff314 · Answer

http://www.wolframalpha.com/input/?i=-0.5x%5E2+%2B+2.79x+-+3.16+%3D+0

anonymous · Answer

OH. THANKS LOL