Let x be the rate of speed of slower cyclist
and x+10 = rate of speed of faster cyclist
Distance = Speed * Time
5x + 5(x+10) = 200
5x + 5x + 50 = 200
10x = 200-50
10x = 150
x = 15
Rate of speed of slower cyclist: 15 mph
Rate of speed of faster cyclist = 15+10 => 25 mph