Question

How do you evaluate `-14c - - 12c + 1= - 7`?

Answer 1

`c=4`

Explanation:

Since we are subtracting a negative `12c` this turns into adding `12c`. Thus, we have

`-14c+12c+1=-7`

We can simplify the terms on the left to get

`-2c+1=-7`

Next, we can subtract `1` from both sides to get:

`-2c=-8`

Next, we can divide both sides by `-2` to get

`c=4`

Hope this helps!

Answer 2

If you treat subtraction of a negative value as addition of a positive, you can simplify the expression and solve: `c=4`

Explanation:

The first thing to do is to combine like terms. both the 14 and 12 are multiplied by `-c`, so we can combine those:

`color(blue)(-14c)-color(green)(-12c)+1=-7`

`rArr -(color(blue)(14)-color(green)(12))c+1=-7`

`rArr -2c+1=-7`

Now, let's move the +1 constant to the Right Hand Side. This will be achieved by subtracting 1 from both sides:

`-2c cancel(+1-1)=-7-1`

`rArr -2c=-8`

Finally, we divide both sides by any constants that our unknown variable is multiplied by. In this case, that constant is -2:

`(cancel(-2)c)/cancel(-2)=(-8)/(-2)`

`color(red)(rArr c=4)`