Question 221282
D=RT  OR T=D/R
400/R=160/(R-30)
160R=400(R-30)
160R=400R-12,000
160R-400R=-12,000
-240R=-12,000
R=-12,000/-240
R=50 MPH IS THE SPEED ON THE THE LEVEL TERRAIN.
pROOF:
400/50=160/(50-30)
8=160/20
8=8