Hi
Note: d = r*t or t= d/r
Let x represent the distance the first runner travels, (36-x) will be the other's
each will have traveled the same amount of time
cross multiply to slove for x
10x = 8*36 - 8x
18x = 8*36
x = 16mi
t = d/r
t = 16/8 = 2 hrs
checking our answer
2hr*8mph + 2hr*10mph = 36mi apart