SOLUTION: the total time taken to travel x km at 20 km/h and y km at 30 km/h is 3 hours . the time taken to travel x km at 40 km/h aand y km at 15 km/h is also 3 hours . find x and y

Question 847492: the total time taken to travel x km at 20 km/h and y km at 30 km/h is 3 hours . the time taken to travel x km at 40 km/h aand y km at 15 km/h is also 3 hours . find x and y
Answer by swincher4391(1107) (Show Source): You can put this solution on YOUR website!
x/20 + y/30 = 3
x/40 + y/15 = 3
multiply by 120 just to make everything nice.
6x + 4y = 360
3x + 8y = 360
Multiply the top equation by 2.
12x + 8y = 720
3x + 8y = 360
------------------
9x = 360
x = 40
Plug back in x = 40 where convenient
x/20 + y/30 = 3
40/20 + y/30 = 3
2 + y/30 = 3
y/30 = 1
y = 30

So x = 40, y = 30

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