The answer is 105 and 105 because they did not tell you that one had more than the other, so it's equal. Plus, it could not be 210 or over or 0 or less. It was spilt up equally between both alternate angles, and the lines are parallel, so the angles are equal. So just do 210/2 and get what one of the angles would be. Great question!
You can use models to help you divide by making the number of models as your divisor. For example let's say I am dividing 8 ÷ 2. So you would make 8 circles (doesn't have to be circle it can be whatever like squares) and then make groups of 2 until you run out of circles. Then how many groups there are is your answer. 8÷2=4. Hope I helped!
The difference between 2x+16=14 than 2x+16=x+14 is that you would have to solve x in two different ways like finding the first equation another way than to the second equation ( I think ).
