Answer:
123
Step-by-step explanation:
We can find the answer by solving the two equations simultaneously.
equation 1: y = -0.4x^2 +3xequation 2: x + y = 10
We need to write equation to with y as the subject:equation 2: y = 10 - x
equation 1 = equation 2:
10 - x = -0.4x^2 + 3x0.4x^2 - 4x + 10 = 02x^2 - 20 + 50 = 0(2x - 10)(x - 5) = 0x = -10/2 or x = 5
But x >= 0 (the question says it's a height above the water), so x = 5
Substituting x = 5 into one of the equations:
y = 10 - x
y = 10 - 5
y = 5
So the answer is C
86 feet
Area=l*w
76x=6536
6536/76=86
76(L)*86(W)=6536
