Solve P = a + b + c for c

Step by step

The question

Question: solve for c in P = a + b + c.

We treat the other letters like numbers.

1 c on the left

c is on the right.

We swap the two sides, so c is on the left.

They are still equal.

2 Remove the other parts

We want c by itself.

The a + b is in the way.

To remove a, we take away a.

To remove b, we take away b.

We do it on both sides.

Each pair makes zero.

Cross them out.

So c = P − a − b.

3 Check

Let's check with numbers.

We pick P = 6, a = 2, b = 3.

Our answer gives c = 1.

Now we put all the numbers into the start.

First the left side.

Now the right side.

Both sides are 6.

So our answer is right!

Let's look back.

First: c on the left.

Then: remove the other parts.

Last: check.