## Algebra 1: Common Core (15th Edition)

Answer Choice $F$: $\frac{q \times u}{s}$
Since. $\triangle$$ABC and \triangle$$DEF$ are similar, that means that $\frac{s}{q} = \frac{t}{r} = \frac{u}{?}$. With the equation $\frac{t}{r} = \frac{u}{?}$, if you cross multiply, you get $? \times t = u \times r$ If we divide both sides by $t$, we get $? = \frac{u \times r}{t}$ With the equation $\frac{s}{q} =\frac{u}{?}$, if you cross multiply, you get $u \times q$ = $s$ $\times$ $?$ If you divide both sides by $s$, you get $?$ = $\frac{u \times q}{s}$ The answer is either $\frac{u \times r}{t}$ or $\frac{u \times q}{s}$ Answer choice $F$ shows $\frac{q \times u}{s}$, which is the same thing as $\frac{u \times q}{s}$, so that is the answer.