
Andy C. answered 02/08/18
Tutor
4.9
(27)
Math/Physics Tutor
distance = rate x time
300 = R x T
300 = (R+10)(T-1)
RT = RT - R + 10T - 10
0 = 10T - 10 - R
0 = 10(T-1)-R
R = 10(T-1)
R/10 = T - 1
T = r/10 + 1
300 = r ( r/10 + 1)
300 = r^2/10 + r
3000 = r^2 + 10 r
0 = r^2 + 10r - 3000
0 = ( R + 60)( R - 50 )
R+60 = 0 ---> results in negative speed
r-50 = 0 ---> r = 50
300 km at 50 km per hour is 6 hours
300 km at 60 km per hour is 5 hours