Answer
55 mph to Tucson, 66 mph from Tucson
Work Step by Step
To Tucson: $330 = x*(330/x)$
From Tucson: $330 = (x+11)*(330/(x+11))$
$330/x = 1+ (330/(x+11))$
$330/x*(x)(x+11) = 1*(x)(x+11)+ (330/(x+11))*(x)(x+11)$
$330 *(x+11)=(x)(x+11) + 330*x$
$330x+3630 = x^2+11x+330x$
$330x+3630 = x^2+341x$
$330x+3630-330x-3630 = x^2+341x-330x-3630$
$0=x^2+11x-3630$
$0=(x-55)(x+66)$
$x-55=0$
$x=55$
$x+66=0$
$x=-66$
We want a speed, so $x\ne-66$. $x=55$
$x+11$
$55+11=66$