Question 68332
This is solving for the variable a :
The equation is 5a=2a-9
To solve for the variable be sure to combine terms with the same variable. that means 5a and 2a. since 2a is smaller than 5a, we are going to eliminate 2a by adding the inverse which is -2a. we will do it both sides 

5a + (-2a) = 2a + (-2a) - 9
5a - 2a = 2a - 2a - 9
3a = 0 - 9
3a = -9      Then we are going to eliminate 3 so that what will be left is a. We are going to do that by multiplying the inverse of 3 which is 1/3.

{{{3a (1/3) = -9 (1/3)}}}
{{{a = -9/3}}}
a = -3

Checking:
 5a = 2a - 9 where a = -3
5(-3) = 2(-3) - 9
-15 = -6 -9
-15 = -15   True


Therefore a = -3