Write an equation in point-slope form for the line through the given point with the given slope.

Step one 
Write the equation with a slope of - 4/5

Notice that -4/5 = - 0.8

So the equation so far is
y = -0.8x + b 

Step Two
Use the point to find b
When x = - 2 then y = - 5
-5 = -0.8(-2) + b
-5 = 1.6 + b              Subtract 1.6 from both sides.
-5 - 1.6 = b
-6.6 = b

Step 3
Write the complete equation
y = - 0.8x - 6.6

Comment
The fact that you are given a fraction for the slope makes me think that the answer should reflect a fraction. If you have choices, you should give them.
  

Answer: v= lwhstep by step explanation: length x width x heightl = 12kmw = 6kmh = 6km12 x 6 = 7272 x 6 = 432therefore your answer would be c) 432 km^3