Question

ABC is parallel to DEF and BE = EF. Given that

Answer 1

`\begin{gathered} \angle ABE=\angle BEF \\ \text{Because they are alternate angles} \end{gathered}`
`\begin{gathered} \angle EBF=\angle EFB \\ \text{Because} \\ BE\cong BF \\ \end{gathered}`

Now:

`\begin{gathered} \Delta BEF\text{ is an isosceles triangle} \\ \text{Besides:} \\ \angle ABE+\angle EBF+\angle EFB=180 \\ 100+2\angle EBF=180 \\ \angle EBF=(180-100)/(2) \\ \angle EBF=40 \end{gathered}`