Answer
240 or 50 mi/h
Work Step by Step
Time it takes from Ajax to Barrington : x
Time it takes from Barrington to Collins : x+6minutes =x+$\frac{1}{10}$h
Speed from Ajax to Barrington :s
x=$\frac{120}{s}$
x+$\frac{1}{10}$=$\frac{150}{s+10}$
$\frac{120}{s}$+$\frac{1}{10}$=$\frac{150}{s+10}$
multipy by 10s(s+10)
1200(s+10)+s(s+10)=10s(150)
1200s+12000+$s^{2}$ +10s=1500s
$s^{2}$ -290s+12000=0
Quadratic formula:
$290^{2}$-4$\times$12000=36100
s=$\frac{290+or-191}{2}$
s=50 or 240
