hellllllllllllllllllppp please!????????

Answer:
BC = 28
Step-by-step explanation:
Since the triangles are similar then the ratios of corresponding sides are in proportion, that is
[tex]\frac{BC}{EF}[/tex] = [tex]\frac{AB}{DE}[/tex] ( substitute values )
[tex]\frac{BC}{7}[/tex] = [tex]\frac{16}{4}[/tex] = 4 ( multiply both sides by 7 to clear the fraction )
BC = 4 × 7 = 28