Question 688360
D=RT
600=(R+25)T
T=600/(R+25)

450=(R-25)T
T=450/(5-25)

THE 2 T VALUES ARE EQUAL.

600/(R+25)=450/(R-25) CROSS MULTIPLY
600(R-25)=450(R+25)
600R-15000=450R+11250
600R-450R=11250+15000
150R=26250
R=26250/150
R=175 MPH FOR THE PLANE IN STILL AIR.