15-a over 3= -9

Question

how do i solve?

Answer 1

Given [(15 - a) / 3] = -9 , solve for the unknown variable a. 

Since you are solving for a, you want to isolate it to one side of the equation. To do this, first multiply both sides of the equation by 3:

   3 * [(15 - a) / 3] = 3 * -9    ===>   (15 - a) = -27

Now, add 27 to both sides of the equation:

  (15 - a) + 27 =  -27 + 27    ===>  (15 + 27) - a = 0   ===>   42 - a = 0

Add a to both sides of the equation to isolate the a:

  42 - a + a = 0 + a    ===>   42 + 0 = a   ===>   42 = a 

Thus, we arrive at the following answer:     a = 42   

Answer 2

(15-a)/3 =-9

first we need to get the 3 out from under the 15-a

we do that by multiplying everything by 3

now we have 15-a= -9*3

then we want to get a by itself so we -15 from both sides
:
                 -a= (-9*3) - 15              remember to solve what's in the parenthesis first

now we have -a= something;  well we dont want -a 

so we multiply both sides by -1

now a= (-1(-9*3) -15 )               so -9*3 minus 15 multiplied by -1 in that order