Model that describes a city as developing around several centers of

A Model that describes a city as developing around several centers of activity is a multiple nuclei model. It states that cities that emerge along several centers of activity are known as  "nuclei." Each of the nuclei is dedicated to a specific type of land use.  Here service activities like stores, banks, insurance companies, and institutions actively interact. The model points out that even though a city may have begun as a Central Business District (CBD), other smaller centers usually emerge on the outskirts (periphery) of the city closer to the expensive housing areas to allow shorter commutes from city outskirts to create nuclei in parts outside the Central Business District (CBD).

the correct answer is:

multiple nuclei model.

Explanation:

simplify brackets

8 - 2a - 7 = a + 40

simplify 8 - 2a - 7 to -2a + 1

-2a + 1 = a + 40

add 2a to both sides

1 = a + 40 + 2a

simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

subtract 40 from both sides

1 - 40 = 3a

simplify 1 - 40 o -39

-39 = 3a

divide both sides by 3

-39/3 = a

simplify 39/3 to 13

-13 = a

switch sides

a = -13