pls help within 24 hrs

Question

sarah ran 18 km at x km/h while fiona cycled at four times sarah's running speed for 75 km.

if fiona took 6 minutes more to complete her training find value of x.

Answer 1

Sarah ran 18 km at x km/h.

Fiona cycled 75 km with 4 times the speed of Sarah i.e speed of Fiona is 4x km/h.

Time taken by Sarah to complete 18 km is T_S= 18/x hr

Time taken by Fiona to complete 75 km is T_F = 75/4x hr

Now given that, Fiona takes 6 mins or 6/60 hr =1/10 hr more than Sarah,

=> T_F = T_S+1/10

=> 75/4x = 18/x +1/10

multiply by x on both sides

75/4=18 +x/10

=> 75/4-18 = x/10

=> x/10 = 3/4

=> x=3*10/4= 15/2= 7.5 km/hr