Hello! We know that the interior angles of the pentagon sum up to 540°. We know a couple of the angle measurements. Let's add them. 130 + 75 is 205. 540 - 205 is 335. The other 3 angles sum up to 335°. Based off those equations, we will combine like terms. If done correctly, the equation should be like this:
3x - 10 = 335
This is because the x's combine to make 3x, and -35 - 5 + 30 is -10. This will help us find the value of x and find the sum of those angles. Let's start off by adding 10 to both sides. -10 + 10 cancels out. 335 + 10 is 345. That leaves 3x = 345. Now, divide each side by 3 to isolate the x. 3x/3 cancels out. 345/s is 115. Let's plug in the value and see what happens. 115 - 5 is 110. 115 + 30 is 145. 115 - 35 is 80. Let's sum it up. 110 + 145 + 80 is 335. 335 = 335. There. x = 115. The measure of angle B is 110°.
