To solve this, I would just find what two adult tickets and one child ticket wold be worth.
To find that, just do:
5.20 + 9.90 * 2, which makes 25.
So now you just find how many 25s are in 900, or 36.
So 36 children's tickets were sold that day.
Hope I helped :)
Answer:
The slope is: 3
The y-intercept is:
or 
Step-by-step explanation:
The equation of the line in Slope-Intercept form is:

Where "m" is the slope of the line and "b" is the y-intercept.
To write the given equation in this form, we need to solve for "y":

Therefore, you can identify that the slope of this line is:
And the y-intercept is: