Check the picture below.
Make sure your calculator is in Degree mode.
x/110 = (320-x)/90
<span> Cross multiply</span>
90x = 35200-110x
200x=35200
X = 35200/200 = 176 (distance traveled by train going 110 mph
176/110 = 1.6 hours = 1 hour and 36 minutes
Check: 110*1.6 = 176, 90*1.6 = 144
176+144 = 320
it will take 1.6 hours ( 1 hour 36 minutes) for the trains to meet
<h3>
Answers:</h3>

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Work Shown:
Part 1

Notice how I replaced every x with g(x) in step 2. Then I plugged in g(x) = x^2+6 and simplified.
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Part 2

In step 4, I used the rule (a+b)^2 = a^2+2ab+b^2
In this case, a = sqrt(x-1) and b = 5.
You could also use the box method as a visual way to expand out 