Answer:
.
Step-by-step explanation:
Given problem : 
First we convert mixed fraction into improper fractions as

Now , plug these values in the given expression , we get
![\left(-5\dfrac{5}{6}\right)\div\left(-4\dfrac{9}{10}\right)=-\dfrac{35}{6}\div\left(-\dfrac{49}{10}\right)\\\\=\dfrac{-35}{6}\times\dfrac{-10}{49}\ \ \ [\text{By Property of fraction}]\\\\=\dfrac{350}{294}\\\\=\dfrac{25}{21}=1\dfrac{4}{21}](https://tex.z-dn.net/?f=%5Cleft%28-5%5Cdfrac%7B5%7D%7B6%7D%5Cright%29%5Cdiv%5Cleft%28-4%5Cdfrac%7B9%7D%7B10%7D%5Cright%29%3D-%5Cdfrac%7B35%7D%7B6%7D%5Cdiv%5Cleft%28-%5Cdfrac%7B49%7D%7B10%7D%5Cright%29%5C%5C%5C%5C%3D%5Cdfrac%7B-35%7D%7B6%7D%5Ctimes%5Cdfrac%7B-10%7D%7B49%7D%5C%20%5C%20%5C%20%5B%5Ctext%7BBy%20Property%20of%20fraction%7D%5D%5C%5C%5C%5C%3D%5Cdfrac%7B350%7D%7B294%7D%5C%5C%5C%5C%3D%5Cdfrac%7B25%7D%7B21%7D%3D1%5Cdfrac%7B4%7D%7B21%7D)
Hence, the answer is
.
Hello, a sphere has zero vertices.
The common factors for 28 and 42 are 1, 2, 7 and 14.