The answer is D, because you move to the right of the decimal to see if that number is 5 or above. Then you round up, (to 86). :) Hope this was helpful.
All exercises involve the same concept, so I'll show you how to do the first, then you can apply the exact same logic to all the others.
The first thing you need to know is that, when a certain quantity multiplies a parenthesis, you can distribute that number to every element in the parenthesis. This means that

So,
is multiplying the parenthesis involving
and
, and we distributed it:
multiplies both
and
in the final result.
Secondly, you have to know how to recognize like terms, because they are the only terms you can sum. Two terms can be summed if they have the same literal expression. So, for example, you cannot sum
, and neither
exponents count.
But you can su, for example,

or

So, take for example exercise 9:

We distribute the 1.2 through the first parenthesis:

And you can distribute the negative sign through the second parenthesis (it counts as a -1 to distribute):

So, the expression becomes

Now sum like terms:

Is there supposed to be a picture attached? Or is it asking simply what number "base 10 blocks" represents. If so, the answer would be 10. Not sure if that's what the question is asking though! Hope this helps :)
Answer:
The volume of a cylinder is 62.8 cm and the volume of a cone is 20.9 cm³ .
Step-by-step explanation:
Formula


Where r is the radius and h is the height .
As given
A cylinder and cone have the same height and radius. The height of each is 5 cm, and the radius is 2 cm.

Thus

= 62.8 cm³
Thus the volume of a cylinder is 62.8 cm³ .



= 20.9 (Approx) cm³
Thus the volume of a cone is 20.9 cm³ .
Therefore the volume of a cylinder is 62.8 cm and the volume of a cone is 20.9 cm³ .