123 is a linear pair with the inside angle so 180-124= 57. Now we have two inside angles and a triangle has to be 180 degrees so 57+42=99 we know that both angles equals 99 so 180-99=80. The third angle is 81 and is a linear pair with x soooo 180-81=99 X is equal to 99. You can also do corresponding angles and have X be 99 because of the inside angle that’s also 99
