Answer:
motorcycle A: 180 km/h
motorcycle B: 200 km/h
Step-by-step explanation:
To solve this question we need to write a system of equations for A and B, using the equation:
distance = speed * time
The speed of A is 20 less than the speed of B, so:
speedA = speedB - 20
And the time A traveled is 3 minutes (0.05 hours) more than B's time, so:
timeA = timeB + 0.05
Then, using the distance equation, we have that:
distanceB = speedB * timeB
90 = speedB * timeB
distanceA = speedA * timeA
90 = (speedB - 20) * (timeB + 0.05)
90 = speedB * timeB + 0.05 * speedB - 20*timeB - 1
90 = 90 + 0.05 * speedB - 20*timeB - 1
20*timeB = 0.05 * speedB - 1
timeB = (speedB - 20)/400
using this timeB in the distance equation, we have:
90 = speedB * (speedB - 20)/400
90 * 400 = speedB^2 - 20*speedB
speedB^2 - 20*speedB - 36000 = 0
Solving this quadratic equation, we have speedB = 200 km/h
And the speedA is:
speedA = speedB - 20 = 200 - 20 = 180 km/h
because
no matter what your x-value is.