The value of is 10 I think
All you have to do is put the walking amount in for w and basketball in for b. Do it for all of these, if it is less than 400 or greater than 600, it is not a solution.
(4 x 40) + (5 x 40) = 360 so reject because it is less than 400.
I'll let you do the rest.
8.333333
let x=8.33333 and 10x=83.33333
10x-x=83.333-8.333
9x=75
x=75/9
x=25/3
x=8 1/3
Now if you meant:
8.383838 then
100x-x=838.3838-8.3838
99x=830
x=830/99
