Question

`a+3=(2a+7)÷r.` How do you make a the subject of the formula?

Answer 1

`a = (7-3r)/((r-2))`

Explanation:

`a+3 = (2a+7)/r" "larr` multiply both sides by `r`

`color(blue)(rxx)(a+3) = color(blue)(cancelrxx)(2a+7)/cancelr`

`" "ar +3r= 2a+7" "larr` there are two `a` terms#

`" "ar -2a = 7-3r" "larr` re-arrange the `a` terms on one side

`a(r-2) = 7-3r" "larr` factorise

`(acancel((r-2)))/cancel((r-2)) = (7-3r)/((r-2))" "larr` divide both sides by `(r-2)`

`a = (7-3r)/((r-2))`