Solution
For this case we can do the following:
DC= 112 mi
DD= 106 mi
We also know that VC= x+3 mi/ht
Where x is the velocity of Diana
Then by definition of time we have:
t= D/V
And we can do this:
[tex]\frac{112}{x+3}=\frac{106}{x}[/tex]
And we can solve for x on this way:
[tex]112x=106x+318[/tex][tex]6x=318[/tex]
x= 318/6 = 53 mi/hr
VC= 53 +3 = 56 mi/hr
