Solution: $ \displaystyle \angle $ACB = 180°- 35° – 100° = 45°.

$\displaystyle \angle $FED = 180° – 45° – 35° – 100° = 35°.

So, both triangles have exactly the same three angles and are therefore, similar.

Since the triangles are similar:$ \displaystyle \frac{DE}{AB}=\frac{EF}{BC}=\frac{DF}{AC}$

So, $ \displaystyle \frac{y}{7}=\frac{12}{4}=3m$

y = 3 x 7 = 21 and $ \displaystyle \frac{6}{x}=\frac{12}{4}=3$

$ \displaystyle x=\frac{6}{3}=2m$