The sum of two numbers is x. if one of the numbers is 12, what is the other ?

If the sum of two numbers is x

Then the equation is like this:

a+b = x

Then it says one of the number is 12. Change either a or b into 12

12 + b =x

If we want to find the other number, we need the make it into the subject

b = x - 12

Hope that help.

Idon’t know this and this isn’t middle school work

I'm not sure exactly but my best guess would be 1/4