<<<This is the exact same thing as x:6 as 3:9
To find x you need to cross multiply (meaning x will be multiplied by 9; and 3 will be multiplied by 6
The picture below shows the step of cross multiplication
The cross multiplication will give you:
9x = 18
Now you must isolate x. To do this divide 9 to both sides of the equation
9x/9 = 18/9
x = 2
Hope this helped!