4+(5-3)5+7 = 4+2*5+7 = 4+10+7 = 21
Visually, we can see that Player 1 and Player 2 are at the <em>same vertical point</em>, and we can confirm that numerically - both of their y-coordinates are 5. We can also see that it looks like the points mirror each other horizontally; numerically, their x-coordinates are 7 and -7 - the same basic number given different signs.
To find the axis of reflection, we want to find the line that passes right through the middle of the two points which, in this case, is the y-axis. Option 3 is the appropriate response in that light.
Slopes of perpendicular lines are opposite reciprocals of each other. The slope of the given equation (which is in slope-intercept form) is 1, the invisible coefficient of x. The opposite reciprocal of 1 is -1, thus the slope of a line perpendicular to the line y = x + 4 is -1.
Hope this helps.
4(x+7)=8x-20
4x+28=8x-20
28=4x-20
48=4x
x=12
