Solution:
Let the volume (in litres) of acids used be:
x1=amount of 25% acid
x2=amount of 40% acid
x3=3*x2=amount of 60% acid
To answer this question, you would need a protractor, which is a device that measures angle. Because this is a picture, I cannot help you. I'm sorry....
What I can tell you is that the angle is less than 90 degrees.
What are u specifically asking
First you had to expanded form.


Finally you can also add by similar to elements.


Final answer: 
Hope this helps!
And thank you for posting your question at here on brainly, and have a great day.
-Charlie