Question 206886
If ABC is similar to DEF, then the corresponding sides form a ratio. In other words, the ratio of AB to DE is the same as the ratio of BC to EF. Similarly, the ratio of BC to EF is equal to the ratio of AC to DF.



What this means is {{{AB/DE=BC/EF}}} and if you plug in the given lengths, you get {{{4/10=8/20}}} (which is indeed true).


Furthermore, this means that {{{BC/EF=AC/DF}}} and plugging in the given values gets us {{{8/20=11/n}}}. So all you need to do from here is solve for 'n'



Note: because all the ratios are equal, we can also solve the equation {{{4/10=11/n}}} and get the same answer.