Question 634468
Let d be the distance the fastest plane travels. Let s be the speed of the fastest.

{{{d/s=3}}}

{{{(2475-d)/(s-75)=3}}}

{{{d=3*s}}}

{{{(2475-3*s)/(s-75)=3}}}

{{{2475-3*s=3*(s-75)}}}

{{{-6*s=-2475-225}}}

{{{s=2700/6=450}}}

So the faster plane travels at 450 mph and the other plane travels at 375 mph.