Question 40648
600/S=(600/(S+20))+1 OR 600/S=(600+S+20)/(S+20) OR 600(S+20)=600S+S~2+20S OR 
600S+1200=600S+S~2+20S OR 1200=S~2+20S OR S~2+20-1200=0 OR (S+120)(S-100)=0 or

S=100 & S+20=120  PROOF 600/100=6 HOURS & 600/120=5 & 6-5=1 HOUR DIFFERENCE