distance, speed, and time question

Question

luisa travels 25 km in 15/4 hours. She walks part of the way at 4km/h and cycles the rest at 12km/h. How far did she walk?

Answer 1

Let x = time that she walked

Then, 15/4 -x = time that she cycled

 

Distance = (Rate)(Time)

 

Distance walking + Distance cycling = 25

 

4x + 12(15/4 - x) = 25

 

4x + 45 - 12x = 25

 

-8x + 45 = 25

 

-8x = -20

 

x = 2.5 hours

 

Distance that she walked = (Rate of walking)(Time walking)

 

                                             = (4 km/hour)(2.5 hours)

 

                                             = 10 km