Since triangle ABC is an isosceles triangle, the measure of angle BAC is equal to the measure of angle ACB. Angle ABC = 80 degrees, leaving 100 degrees to be divided equally for the measures of the other two angles. Now that you know that angle ACB = 50 degrees, you can calculate the value of angle ACD and determine that angle ACD = 130 degrees. Triangle ACD is also an isosceles triangle, and the two equal legs are AC and CD. Since angle ACD = 130 degrees, the other two angles have a total of 50 degrees. Splitting the 50 degrees equally between the two angles gives you 25 degrees as the value of angle CAD, which is labeled "x."
U would add it even though it looks like u need to multiply but u don’t. In order to add, u need to find the lcd of them both which is 12. 10/12 + 9/12. 19/12 or 1 7/12.