Question

Make x the subject of the formula.
A-x=xr/t​

Answer 1

make x the subject means write all terms in terms of x

look at attachment.

Answer 2

`A-x=\cfrac{xr}{t}\implies At-xt=xr\implies At=xt+xr \\\\\\ At=x(t+r)\implies \cfrac{At}{t+r}=x`