26.9k views
5 votes
-40= -8c

i never understand this

2 Answers

3 votes
I Think You Have To Divide 40 By 8
User Verybadbug
by
6.5k points
4 votes
-8c means -8 times c. The c is a placeholder for a number. Think of it as a box that holds the number.

The value that goes in the box is 5 because -8 times 5 = -40. We can find this through trial and error. Or the best way is to divide both sides by -8. Why divide? Because we want to undo what is happening to the variable to isolate it.

So divide both sides by -8 to get...
-40 = -8*c
-40/(-8) = -8*c/(-8)
5 = c
c = 5

And as a check, we can plug this value of c back into the original equation
-40 = -8*c
-40 = -8*5
-40 = -40
so the answer checks out
User Adam Griffiths
by
6.0k points