Question 637387
Let
Speed of slower train = x
Speed of faster train = x+10.3


Speed of slower train + Speed of faster train = Sum of speeds 
x+x+10.3=723.7
2x+10.3=723.7
2x=723.7-10.3
2x=713.4
2x/2=713.4/2
x=356.7



Speed of slower train = x = 356.7
Speed of faster train = x+10.3 = 356.7+10.3=367