80. a certain insect has a mass of 75 milligrams.
what is the insect’s mass in grams?
f. 0.075 g
g. 0.75 g
h. 7.5 g
j. 75 g
k. 7,500 g

Since 1 milligram = 0.001 grams you just have to multiply 75 milligram by 0.001 grams in order to get the grams.
75 x 0.001= 0.075 grams so the answer is F.

I think the missing part of the box volume is 12 inches and the volume of the box is 84 inches in total. 
Here's how I got it.

First, I multiply 6 by 4 for the base and then multiply the answer, 24 by 3 to get 72 inches.

Next, I need to find the other small box on top of the it. So then I multiply the width, which is 1.5 feet by the length( up and down ) which is 2 because I subtracted the other lengths( up and down ), 8 by 6.

Finally, if you multiply them together, you'll get 3 because 1.5 x 2 = 3. 
To find out what to multiply them by you need to find the height which is 4 inches ( it's on the bottom already. ) 

3 x 4 = 12. 12 + 72 = 84

So, the volume is 84.  ;)