Answer:
<u>See below:</u>
Step-by-step explanation:
Let the angles be 5x , 4x , 3x.[Since the angles are in ratio 5:4:3 ] respectively.
We know that sum of all angles of a triangle is 180°.
So,

Now Find the value of x of this equation.





Now,
Multiply each ratio given by 15 which is the value of x we got.
That is;



Hence,the measurements of the angles of the triangle would be 75°[First Angle],60°[Second angle],and 45° [Third Angle].

I hope this helps!
Let me know if you have any questions.