The average of two numbers is x. If one of the numbers is 3m-1, then the other number, in terms of x and m, is...

Is this how you do it?

Please explain how and show work......

(3m-5)+(?)/2=x

You are on the right track, but make sure you put brackets around the whole thing, the way you have it, only the (?) part is divided by 2

let the second number be y

then ( 3m-1 + y)/2 = x
multiply both sides by 2

3m - 1 + y = 2x
y = 2x - 3m + 1