Answer:
x = 9
Step-by-step explanation:
1/4(8x+12) =21
1/4 * 8x = 2x
1/4 * 12 = 3
2x + 3 = 21
21 - 3 = 18
2x = 18
18/2 = 9
x = 9
you need to know the mass of the jewelry box before you can know the volume but i can help you multiply th 15 and the 10 to get the mass most likely then divided what you have from 15 x 10 by the depth and you have your answer just be sure to round it off!
Answer:

Step-by-step explanation:
In right triangles only, the tangent of an angle is equal to its opposite side divided by its adjacent side.
Therefore, we have the following equation:

Solving, we get:

Also in right triangles only, the cosine of an angle is equal to its adjacent side divided by the hypotenuse of the triangle.

We can also use the Pythagorean theorem now that we've found BC. However, if you choose to do so, make sure you don't use a rounded value for BC, as that could cause a notable deviation in your final answer.
Using the Pythagorean theorem to verify our answers:

The area of the parallelogram is 391 cm².
The area of a parallelogram is calculated by multiplying the base by the height.
A=b×h
A=23 cm×17 cm
A=391 cm²