How do you solve 10/12=x/18?

2 Answers
Feb 17, 2017

x = 15

Explanation:

You an solve this in two ways: proportionality or just rearranging the equation

Rearranging the equation
You can multiply 10/12 by 18 to leave x to one side.
10/12 * 18 = x
x = 15

Proportionality
You can work out the proportion between 12 and 18, which will be the same for 10 and x.
so 18/12 = 1 1/2
Therefore, if we multiply 10 by 1 1/2 we get the value of x which is 15

Feb 17, 2017

x=15

Explanation:

Using first principles

Multiply both sides by color(red)(18)

color(green)(10/12color(red)(xx18)" " =" " x/18color(red)(xx18))

color(green)(10/12color(red)(xx18)" " =" " x color(red)(xx)(color(red)(18))/18)

But 18/18=1 so x xx18/18 =x xx1=x giving:

(10xx18)/12=x

Write as " "x=(10xx18)/12" "=" "(2xx5xx2xx3xx3)/(3xx4)

x=(2xx2)/4xx3/3xx5xx3" " =" " 1xx1xx15

........................................................................
or if you prefer:

x= "(cancel(2)^1xx5xxcancel(2)^1xx3xxcancel(3)^1)/(cancel(3)^1xxcancel(4)^1) = 5xx3=15