Answer:
50 km/hr
Step-by-step explanation:
OK, this is how I solved this problem.
Let r = original rate of speed
t = time after the stop to finish the trip
Time for trip without stopping is 225/r
(1) 1.5 + .5 + t = 225/r This is a time equation
(2) 1.5r + t(r + 10) = 225 This is a distance equation
(1) 2 + t = 225/r (2) 1.5r + tr + 10t = 225
2r + tr = 225
tr = 225 - 2r 1.5r + 225 - 2r + 10(225/r - 2) = 225
t = 225/r - 2
-.5r + 225 + 2250/r - 20 = 225
-5r + 2250 + 22500/r - 200 = 2250
-5r^2 + 2250r + 22500 - 200r = 2250r
5r^2 + 200r - 22500 = 0
5(r^ + 40r - 4500) = 0
5(r - 50)(r + 90) = 0
r = 50 or r = -90
The rate cannot be negative, so the original speed 50 km/hr
This not an easy problem and I hope you were able to follow my work
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