Alex is making a square with 4 corners, brittanie is making a triangle with 3 corners. That's the difference, hope it helped a little, it's not a full answer but maybe it will help.
Answer:
<em>x = 0.05</em>
<em>x = 1.57</em>
Step-by-step explanation:
The given equation is:

Moving all terms to the left side:

Now we define a function:

The solutions of the equation are the values of x such that y=0.
Since the function cannot be solved by algebraic methods, we use a graphing tool.
Those points where the graph crosses the x-axis are solutions of the equation.
Please refer to the graph in the figure below.
We can clearly identify there are two solutions at
x = 0.05
x = 1.57
X is 10
I have shown the calculation in the attachment.
I'd do 9x4=36 because the 9 is from your money and the 4 is from your books. Now since you want to find out how much 4 books cost you just multiply that by 9