Question

T=pd/2xsolve for Xi always get confused when theirs more then one letter

Answer 1

When there's more than one letter, and you just have to solve for one variable, you can just solve it like you would any other equation. Treat the other variables like numbers and add, subtract, multiply, and divide them to both sides of the equation in order to isolate the variable you want to solve for.

$t= \frac{pd}{2x} \\ \\ t*2x= \frac{pd}{2x}*2x \\ \\ 2tx=pd \\ \\ \frac{2tx}{2t} = \frac{pd}{2t} \\ \\ x=\frac{pd}{2t}$

Answer 2

OK.  Then let's just give the other letters different names.

Instead of      T = p d / 2x

let's write      Tiger = pig dog / 2x

Multiply each side by 2x :      2x Tiger = pig dog

Divide each side by Tiger :      2x = pig dog / Tiger

Now divide each side by 2 :      x = pig dog / 2 Tiger

Of course you would not hand it in on a homework sheet like that.
You would change it back to
                                             x = p d / 2 T  .