Question 729295
D=RT
975=(R+40)T
T=975/(R+40)
800=(R-30)T
T=800/(R-30)
THE TIMES ARE EQUAL SO:
975/(R+40)=800/(R-30)
975(R-30)=800(R+40)
975R-29,250=800R+32,000
975R-800R=32,000+29,250
175R=61,250
R=61,250/175
R=350 MPH. IN STILL AIR IS THE SPEED.
975=(350+40)T
975=390T
T=975/390
T=2.5 HOURS
PROOF:
800=(350-30)*2.5
800=320*2.5
800=800