A and B are vertical angles. If m_A = (3x - 30)° and m
then find the value of x.
B = (2x - 9)

Work Shown:

Vertical angles are always congruent.

This means they are equal in measure.

A = B

3x-30 = 2x-9

3x-2x = -9+30

x = 21

Side note:

if x = 21, then,

A = 3*x-30 = 3*21-30 = 33 degrees

B = 2*x-9 = 2*21-9 = 33 degrees

When a geologists studies the rock, he must be interested in lithosphere, the sphere of Earth which has the rock.  

Option D

Explanation:

Lithosphere is the sphere with the rock and soil component, broadly speaking the land. Lithosphere is the sphere where the rocks are present above the mantle (upper mantle) and the crust.

They had the rock which are solid in state and are consider to be of elastic nature with low ductility. There are broadly two main categories based upon the location of their presence, which are oceanic and continental.