Answer:
x = 17.5
Step-by-step explanation:
[tex] \triangle ABC \sim \triangle DEF... (given)[/tex]
[tex] \therefore \frac{AB}{DE} = \frac{BC}{EF} [/tex]
[tex] \therefore \frac{10}{4} = \frac{x}{7} [/tex]
[tex] \therefore 2.5 = \frac{x}{7} [/tex]
[tex] \therefore 2.5\times 7= x[/tex]
[tex] \therefore 17.5= x[/tex]
[tex] \therefore x = 17.5[/tex]