The missing length is 12km (i never promised anything xd)
I believe that the answer is C.
Let the width of the rectangle be x
Then length =x-4
Area=x(x-4)=140
x²-4x=140
x²-4x-140=0
x²-14x+10x-140=0
x(x-14)+10(x-14)=0
(x-14)(x+10)=0
Therefore,length=14 cm and width=10 cm
1 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Every point on the x-axis has y-coordinate 0.
Let y = 0, and solve for x.
y = -5x + 5
0 = -5x + 5
5x = 5
x = 1
The line crosses the x-axis at x = 1.