-3(n+4)-2(n+4)=-30

Question

please help explain and solve  this equation

Answer 1

Hi Yose;

-3(n+4)-2(n+4)=-30

Let's distribute...

-3n-12-2n-8=-30

Please note that in the first parenthetical formula, -3 changes n+4 into -n-4 as it is multiplied by 3 for a final result of -3n-12.

 

Please note the fact that subtracting 2, is the same as adding negative 2.  Henceforth, the second parenthetical formula of n+4 becomes -n-4, as it is multiplied by 2 for a final result of -2n-8.

 

Let's combine like terms...

-3n-12-2n-8=-30

-5n-20=-30

Let's isolate n...

Let's add 20 to both sides...

20-5n-20=-30+20

-5n=-10

Let's divide both sides by -5...

(-5n)/-5=-10/-5

n=2

Please note the fact that a negative number divided by a negative number becomes a positive number.

If we were multiplying two negative numbers, the result would also be a positive number.

 

Let's check our results with the original equation...

-3(n+4)-2(n+4)=-30

-3(2+4)-2(2+4)=-30

-3(6)-2(6)=-30

-18-12=-30

-30=-30

All good!