Plug the two points into the slope formula.
m = y2-y1/x2-x1
m = (-4 - 5)/(0 - 2)
m = -9/-2
m = 4.5
So the slope is 4.5
Part (b)
We use the result of part (a) and plug in (x,y) = (0,0). This is directly from the initial condition y(0) = 0.

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This means,

is the solution with the initial condition y(0) = 0.
5.476 rounded to the hundredths place = 5.48
The answer to 2-(-8)+(-3)= 7