Question 601553
{{{t=d/r}}}
Let rate of older plane = x and rate of newer plane = y
{{{t=900/x}}}
{{{t=1200/y}}}
Since both planes travel the given distance in the same time; their times are equal, then:
{{{900/x=1200/y}}}
{{{900y=1200x}}}
The newer plane travels 200 mph faster than the older (given):
{{{y=x+200}}}
Substitute y:
{{{900(x+200)=1200x}}}
{{{900x+180000=1200x}}}
{{{180000=300x}}}
{{{600=x}}}
The rate of the older model jet plane is 600 mph