Question 154360
"Elena bicycles 5km/h faster then Carlos" __ E=C+5


d=rt __ t=d/r


" In the same time it takes Carlos to bicycle 39km, Elena can bicycle 54km" __ 39/C=54/(C+5)


"cross" multiplying __ 39C+195=54C __ subtracting 39C __ 195=15C __ dividing by 15 __ 13=C


substituting __ E=(13)+5 __ E=18