Okay so 60° and z° equal 180° and (10x-70)° + z°=180. z eauals 120° so 120°-180°=60°! so (10x-70)°=60° now we have to solve this. subtract 70 from both sides so now you have (10x)=130 because negative 70 subtract by 60 eqauls a postive 70. divide 130 by 10 and x = 13
