It’s might be D
Explanation 20 characters
It's the sum of the three masses:

Linear relationships can be represented in several different ways: a graph, an equation, or a list of points. ... We can then graph the line to find the y-intercept, and use the slope and y-intercept to write an equation of the line.
Answer:
Scientific notation: 4 ⋅ 10 -4
expanded form: 0.0004
Answer: 6
Step-by-step explanation:
15/4 divided by 5/8= 6