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Let x be the speed of the bus, in km/h.
Then the speed of matatu (don't know what is it) is (x+20) km/h.
The time for bus is hours.
That for matatu is hours.
The condition says that
= (8/5 is 96 minutes = hours).
To solve it, multiply both sides of your equation by 5x*(x+20). You will get
1400(x+20) - 1400x = 8x*(x+20).
Simplify and solve this quadratic equation.
Choose the positive root from the two.
Good luck !.
*** I solved it mentally and got the answers 50 km/h and 70 km/h ***
If you still have questions or want to report your answer, I will be glad to receive it from you.
For it, use the TY form and do not forget to refer to the problem ID number.
It is 1089807, by the way.
Also, do not forget to send your thanks to me after completing your solution.
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Just learned from Wikipedia about matatu . . .