Answer:

Step-by-step explanation:
Before number line can be drawn, there is need to find the value of x in the inequality given. Thus,

Divide both sides by 2


The number line is indicated in the attached picture.
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6x + 45 + 3x = 180
9x - 45 = 180
9x = 135
x = 15
Area=length*width
let the sides perpendicular to the river be x
then the side parallel to the river is 4,700-2x
A(x)=x(4700-2x)
A(x)=4700x-2x^2
This a quadratic function with a=-2 and b=4700
thus
Maximum area occurs where x=-b/2a=-4700(-2*2)=1,175 ft
length=4700-2(1175)=2,350 ft