9-5y , o tambien puede ser -y-1
The second result is more precise because it's in millilitre,so if the first were to be fully precise,it should have been 78.6 cm.
Hope this helps!

just comment if you would like to know how I did it
Answer:
- 35 1/3°
- 54 2/3°
Step-by-step explanation:
Angle AOB and BOC create a complementary angle. This means when two angles sum up to 90°. We can write an equation for this problem;
(x + 8) + 2x = 90
~Remove parenthesis
x + 8 + 2x = 90
~Combine like terms
3x + 8 = 90
~Subtract 8 to both sides
3x = 82
~Divide 3 to both sides
x = 82/3 or x = 27 1/3
Use what have for x to solve for the angle measures.
Angle AOB:
x + 8
(27 1/3) + 8
35 1/3°
Angle BOC:
2x
2(27 1/3)
54 2/3°
Check.
35 1/3 + 54 2/3 = 90°
Best of Luck!
For the first one we will use the Law of Sines. First off, though, we need to find angle C's measure. By the Triangle Angle-Sum Theorem, the angles of a triangle all add up to equal 180. Therefore, angle C is 180-15-20 which is 145 degrees. Now we will set up the Law of Sines ratios.

. Solving for BC, we have

and on our calculators we find that BC is 4.5, last choice above. For the second one, the sin ratio is the side opposite the reference angle over the hypotenuse. The cos ratio is the side adjacent to the reference angle over the hypotenuse. The side opposite angle R is r, and the hypotenuse is q, so the sin R = r/q. For the cos P, the side adjacent to angle P is r, and the hypotenuse is q, so the cos P = r/q. Obviously, those 2 ratios are the same, so your choice is the very first one given.