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4 votes
Solve -5(3n + 4) = 40.
-4
-3
3
4

User Gunty
by
7.6k points

2 Answers

2 votes
-5(3n + 4) = 40

Simplify.

-15n - 20 = 40

Add 20 to both sides.

-15n = 40 + 20

Simplify.

-15n = 60

Divide both sides by -15.

n = 60 / -15

Simplify.

n = -4

Check our work by simply plugging -4 in for n in the given equation.

-5(3n + 4) = 40

-5(3(-4) + 4) = 40

Simplify.

-5(-12 + 4) = 40

Simplify.

-5(-8) = 40

40 = 40

So, n = -4

~Hope I helped!~
User Wienke
by
7.0k points
5 votes
Our current equation is:
-5(3n + 4) = 40

To solve for this, we need to use the Distributive Property. The Distributive Property allows any number/variable outside of the parenthesis to be multiplied by all numbers/variables inside of the parenthesis.

For example, 3(2 + 3) would be:
3(2) + 3(3)
6 + 9
15.

Now that we've defined our terms and provided an example, I think we're ready to solve.

-5(3n + 4) = 40
-5(3n) + -5(4) (multiplying a positive by a negative makes a negative)
-15n -20 = 40
Add 20 to both sides to get -15n by itself.
-20 + 20 = 0
40 + 20 = 60

We now have:
-15n = 60

Divide both sides by -15 to solve for n.
-15n / -15 = n
60 / -15 = -4

N = -4.

Your answer is A.) -4.

I hope this helps!
User Keith Morgan
by
7.4k points