Question 1.

$\frac{v(b)}{v(a)}$ = $\frac{m-45}{m}$ …..(1)

where ‘”m” is the entire distance of the race track.

Moreover $\frac{v(b)}{v(c)}$=$\frac{m}{m-50}$ …….(2)

and finally $\frac{v(a)}{v(c)}$=$\frac{m}{m-90}$ ……(3)

Multiplying (1) and (2) we get (3). 

$\frac{m}{m-90}$=$\frac{m}{m-45}$($\frac{m}{m-50}$)

Solving we get m=450 which is the length of the entire race track