<span>For the Vertical Angle theorem, if a slant line is intersected by a horizontal, the opposite angles must be equal. In here, he stated that the sum of angle 1 and angle 4 and the sum of angle 3 and angle 4 are each equal to 180 degrees. It means that the sum of angle 1 and angle 4 is equal to the sum of angle 3 and angle 4 by the transitive property of equality. </span>
Let f be the fathers age and let s be the sons age
f = 60 s = 30
when f = 45
s = 15 which is only a third if his fathers age
when f = 40
s = 10 which is a quarter of his fathers age
therefore when his father was 4 times his age, the son was 10
What do the places mean? I’d say the signs are negative since both values are (-3) and (-5), but i don’t know what you mean by placed - if they were placed in a number line, it would go 3 and 5 values left or down.