I don’t know how those answers exist but the correct answer here is 10, 16-6 = 10 yds.
Let's say that the value invested in the account with a rate of 8% is "x", then the amount invested in the account with a rate of 12% is:

To calculate the total interest we need to calculate the interest of each individual account and sum them:

The total interest is the sum of the two expressions above:

The value invested in the account with 8% interest is 830, the one invested in the account with 12% interest is 1280.
<h3>
You are correct. The answer is the second choice.</h3>
BC = JC by the single tickmarks shown
CD = CD because of the reflexive property
The angles between these two pairs of sides, that you've marked in the second answer choice, are needed to use SAS (side angle side).
See the diagram below. In the diagram, angle BCD (green) is between segments BC and CD. Also, angle JCD (blue) is between JC and CD.
To answer the given above, multiply the whole equation with least common multiple of the denominators which is 5n. Shown below,
(4/5n - 1/5 = 2/5n) x 5n
4 - 1(n) = 2
-n = -2, n = 2
The answer is not among the choices, it could have been letter A except that the constant in A is negative.