Answer:
3,451 cm³
Step-by-step explanation:
The ball is a sphere.
Formula for finding the volume of a sphere = ⁴/3*πr³
Volume of the 3 balls = 3(⁴/3*πr³)
Where,
radius (r) = ½ of diameter = ½(13) = 6.5 cm
Plug in the values into the formula:
Volume of the 3 balls = 3(⁴/3*π*6.5³)
= 4*π*274.625
= 3,451.03953 ≈ 3,451 cm³
The denominator of the second fraction can be factored as (a-2)(2a-7), then it becomes doable. You cancel the (2a-7) factors, and are left with:

Do note that you have erased the fact that a≠0 and a≠7/2, so you should always mention that.
In its normal way, For example: 214, Write it in the way it is Usually written.
Set up an equation 20=k(0.4)....to find k divide 20 by 0.4