You have to use what is given to solve. For example, in number 46 there is a little box in the angle. That means it is 90°. One of the angles inside that 90° is also given that is 68°. So you have to set up and equation 86+(x+9)=90
Then you solve this like i regular equation. If there is a straight line, that is 180° and you set the equation to 180
46) x=13
47) x=17
48) x=19
49) x=13
