If y=-7 when = -21, determine x when y= 9

Correct Question :-

Given :-

We need to find :-

Solution :-

Using proportion ,

By means & extremes ,

=> - 7x = - 21 × 9

=> x = ( - 21 × 9 ) / - 7

=> x = 3 × 9

=> x = 27

Hence , when y = 9 → x = 27

the answer will be the last one

for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.