The correct answer is:
x = (r+st)/r; or
x = 1+ (st)/r.
Step-by-step explanation:
To isolate the variable x, we must cancel everything else on that side of the equals sign.
We begin with st, since it is farther from x. Add st to each side:
rx - st = r
rx - st + st = r + st
rx = r + st
Now we divide each side by r:
rx/r = (r+st)/r
x = (r+st)/r = r/r + st/r = 1 + (st)/r