To answer this problem, one way is to use the calculator and add directly the two numbers and get the average between the two. The answer is 25/77. We can also get this number by getting the LCM of the denominators which is 77. 2/7 is equal to 22/77 while 4/11 is equal to 28/77. 0.5*(22 +28) is equal to 25. Hence the answer is 25/77.
The first blank is "division" and the second blank is "multiplying"
12 / (3) = 4
5 x 3 = 15
15 + 4 = 19
For this case we have that by definition of trigonometric relations that the sine of an angle is equal to the opposite leg to the angle on the hypotenuse. That is to say:

Clearing the value of "a":

Rounding off we have:
17.7
Answer:
Option B