Sam swims P +10 while
Tom swims P-10
Nex Sam has swimmed 3P-80 while
Tom has swimmed P+80 Where P = pool length
Since theyswim at a constant ratio:
(p+10)/(p-10) = (3p-80)/(p+80) cross multiply
p^2 + 80p +10p +800 = 3p^2 -30p -80p +800 simplify
p^2 +90p +800 = 3p^2 -110p +800
90p = 2p^2 -110p
0= 2p^2 -200p
0= p-100 or p=100m = pool length