Question

How do you solve `\frac { 3} { x + 4} = \frac { 9} { x + 8}`?

Answer 1

`x=-2`

Explanation:

`color(blue)(3/(x+4)=9/(x+8)`

Cross multiply `color(orange)(a/b=c/drarrad=bc`

`rarr3(x+8)=9(x+4)`

Divide both sides by `3`

`rarrx+8=3(x+4)`

`rarrx+8=3x+12`

Subtract `8` from both sides

`rarrx=3x+4`

Subtract `x` from both sides

`rarr0=2x+4`

`rarr2x+4=0`

Subtract `4` from both sides

`rarr2x=-4`

Divide both sides by `2`

`color(green)(rArrx=-2`

Hope this helps ... :)