I just took a screenshot of it, but I have no idea how to do this

84°

Step-by-step explanation:

Solve for n. Note that the angle measurements of a circle will equal 360°. Set all the angles = 360°.

7n + 12 + 13n - 16 + 6n = 360

Combine like terms:

(7n + 13n + 6n) + (12 - 16) = 360

26n - 4 = 360

Isolate the variable, n. Note the equal sign, what you do to one side, you do to the other. First, add 4 to both sides:

26n -4 (+4) = 360 (+4)

26n = 360 + 4

26n = 364

Next, divide 26 from both sides:

(26n)/26 = (364)/26

n = 364/26

n = 14

Next, plug in 14 for n in the angle measurement, 6n:

6n = 6(14) = 84°

Note that these are central angles, which means that the arc's will be the same measurement as the angle's measurement.

arcBC = 84°

84° is your answer.

~

3:20

Step-by-step explanation:

Volume of triangular prism

1/2×a×b×c

1/2×5×9×4=90cm³

Volume of a rectangular prism

length ×breadth×height

6×5×20=600cm³

90:600

=3:20