We must calculate the anwer eith the next approach
[tex]\frac{165}{65+x}+\frac{235}{75+x}=5.5[/tex]So, we need to solve for x
[tex]\begin{gathered} \frac{165(75+x)+235(65+x)}{(65+x)(75+x)}=5.5 \\ \frac{12375+165x+15275+235x}{x^2+140x+4875}=5.5 \\ 27650+400x=26812.5+770x+5.5x^2 \\ 5.5x^2+370x=837.5 \\ x=-2.19,x=-69.46 \end{gathered}[/tex]So, to arrive at their destination in 5.5 hours they must drive 2.19 mph over the speed limits.
