The interior angles in any triangle sum to 180 degrees, so the measure of angle E is 180 - 65 - 50 = 65 degrees.
Assuming side d is opposite angle D, side e is opposite angle E, and side f is opposite angle F, we can use the law of sines to determine the side lengths e and f.
[tex]\dfrac{\sin D}d=\dfrac{\sin E}e=\dfrac{\sin F}f[/tex]
[tex]\dfrac{\sin50^\circ}{7.5}=\dfrac{\sin65^\circ}e\implies e\approx8.87[/tex]
Angles E and F have the same measure, so [tex]f\approx8.87[/tex] as well.
