Look for some things that are equal in order to set up an equation.
The key here is that they both ran the same amount of time.
We know that D = RT, so T = D/R.
Find expressions for each of their times.
Let D = the total distance run by Gary (he completed the race)
Then (5/8)D is the distance run by Faizal.
Let F = rate at which Faizal ran the race.
Time for Gary is D / (F + 75), because Gary's speed/rate was 75 m/min faster than Faizal's.
Time for Faizal is (5/8) D / F
These times are equal:
D / (F + 75) = (5/8)D / F (you might want to write this down on paper with horizontal segments for the fractions. Cross multiply to reach:
DF = (5/8)D ( F + 75) , note that both sides are divisible by D
F = (5/8)(F + 75)
Multiply both sides by 8 to clear the fraction (would be my next step).
8F = 5(F + 75)
8F = 5F + 5(75)
3F = 5(75)
F = 5(25) = 125 m/min: this is Faizal's speed.
G = 200 m/min, this is Gary's speed (75 m/min faster)
Gary's distance:
200T (we really do not know the time or actual distance)
Faizal's distance:
125T
Is 125T 5/8 of 200T?
(5/8) 200T = 5(25)T = 125T (check)