Answer:
x = 2
Step-by-step explanation:
Since the triangles are similar then corresponding sides are in proportion, that is
[tex]\frac{AB}{DE}[/tex] = [tex]\frac{BC}{EF}[/tex] , substitute values
[tex]\frac{7x}{7}[/tex] = [tex]\frac{4}{x}[/tex] ( cross- multiply )
7x² = 28 ( divide both sides by 7 )
x² = 4 ( take square root of both sides )
x = [tex]\sqrt{4}[/tex] = 2
