The sum of all the angles of a triangle is 180 degrees. To solve for x you can make a formula of the sum of the angles equal to 180 like so...
(x - 73) + x + 67 = 180
x - 73 + x + 67 = 180
Now you must combine like terms. This means that you must first combing number with the same variables(x and x)...
(x + x) - 73 + 67 = 180
2x - 73 + 67 = 180
Combine like terms -73 and 67...
2x + (-73 + 67) = 180
2x + (-6) = 180
2x - 6 = 180
Now bring -6 to the right side by adding 6 to both sides (what you do on one side you must do to the other). Since -6 is negative on the left side, addition will cancel it out (make it zero) from the left side and bring it over to the right side.
2x - 6 + 6= 180 + 6
2x + 0 = 186
2x = 186
Next divide 2 to both sides to finish isolating x. Since 2 is being multiplied by x, division (the opposite of multiplication) will cancel 2 out (in this case it will make 2 one) from the left side and bring it over to the right side.
2x / 2 = 186 / 2
x = 93
Hope this helped!
~Just a girl in love with Shawn Mendes