How do you solve 10/12=x/181012=x18?

2 Answers
Feb 17, 2017

x = 15x=15

Explanation:

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

Rearranging the equation
You can multiply 10/121012 by 18 to leave x to one side.
10/12 * 18 = x101218=x
x = 15x=15

Proportionality
You can work out the proportion between 12 and 18, which will be the same for 10 and xx.
so 18/12 = 1 1/21812=112
Therefore, if we multiply 10 by 1 1/2112 we get the value of xx which is 1515

Feb 17, 2017

x=15x=15

Explanation:

Using first principles

Multiply both sides by color(red)(18)18

color(green)(10/12color(red)(xx18)" " =" " x/18color(red)(xx18))1012×18 = x18×18

color(green)(10/12color(red)(xx18)" " =" " x color(red)(xx)(color(red)(18))/18)1012×18 = x×1818

But 18/18=11818=1 so x xx18/18 =x xx1=xx×1818=x×1=x giving:

(10xx18)/12=x10×1812=x

Write as " "x=(10xx18)/12" "=" "(2xx5xx2xx3xx3)/(3xx4) x=10×1812 = 2×5×2×3×33×4

x=(2xx2)/4xx3/3xx5xx3" " =" " 1xx1xx15x=2×24×33×5×3 = 1×1×15

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

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