You solve this by using google.com or YouTube.com
Or just pay attention in class to get this.
Since all the sides add up to 10x+2, that means that 10x-2-<side1>-<side2>=<side3>. Plugging it in, we have 10x-2-5x-(2x+9)=side3, and 5x-2-(2x+9)=side3, then expanding it to 5x-2-2x-9=3x-11=side3
1: 5 2: 9 or 10
For question 1 we can round 115 to 100, 5x100 is 500 which is closer to 545 than 7x100 = 700.
9/72
I forgot how to do this
36 I believe.....................
