Question

If rx – st = r, which expression represents r.

Answer 1

`{ \tt{rx - st = r}}`

» Collect like terms, r terms on the left hand side by subtracting r from both sides and adding st to both sides

`{ \tt{(rx - st) { \green{ - r + st }} = r{ \green{ - r + st}}}} \\ { \tt{rx - r = st}}`

» On the left hand side, factorise out r

`{ \tt{ \green{r(x - 1)} = st}} \\ \\ { \boxed{ \tt{ \blue{ \: r = (st)/(x - 1) }}}}`