How do you solve \frac{x + 7}{x} = \frac{7}{9}?

1 Answer
Mar 5, 2018

x = -63/2 or -31.5

Explanation:

(x+7)/ x = 7/9

There may be more complex, quicker ways to solve this, but by simply moving around the numbers in order to isolate x, we can solve this question.

(x+7)/x xx 9= 7/color(red)(cancel(color(black)(9))) color(red)(cancel(xx 9))

((x+7) xx 9)/ x = 7

(9x + 63)/ color(red)(cancel(color(black)(x))) color(red)(cancel(xx x)) = 7 color(red)(xx x)

9x + 63 color(red)(-7x)= color(red)(cancel(color(black)(7x) -7x))

2x color(red)(cancel(color(black)(+63) -63))= 0 color(red)(-63)

(color(red)(cancel(color(black)(2)))x)/color(red)(cancel(2)) = -63/color(red)(2)

color(blue)(x = -63/2)

color(blue)(x = -31.5)

ul(color(white)(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx))

We can check this by substituting the result for the Pronumeral.

(x+7)/ x = 7/9

(-31.5 + 7)/ -31.5 = 7/9

(24.5 color(red)(xx 2))/ (31.5 color(red)(xx 2)) = 7/9

(49 color(red)(-: 7))/(63 color(red)(-: 7)) = 7/9

7/9 = 7/9

ul(color(white)(xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx))