Given tan(α)=pq\tan(\alpha) = \frac{p}{q}tan(α)=qp and tan(β)=rs\tan(\beta) = \frac{r}{s}tan(β)=sr, find tan(α−β)\tan(\alpha - \beta)tan(α−β) in terms of p,q,r,sp, q, r, sp,q,r,s.
ps+qrqs−pr\frac{ps + qr}{qs - pr}qs−prps+qr
ps−qrqs+pr\frac{ps - qr}{qs + pr}qs+prps−qr
ps−qrpr+qs\frac{ps - qr}{pr + qs}pr+qsps−qr
pq−rsqs+pr\frac{pq - rs}{qs + pr}qs+prpq−rs