Solving Equations Using Subtraction

Let's solve x+7=11.

First draw a picture of x+7=11.

The left side of the equation is x+7. Let's draw an x and a 7 on the left side of our picture.

The right side is 11, so let's draw an 11 on the right.

Can you think of a number to replace "x" so that the left side and the right side add up to the same total?

For this puzzle, you should pick x=4, because then both sides will total up to 11.

Here again is a picture of our equation:

How can we solve this without guessing?

Let's see if we can come up with a strategy to make this equation easier.

To turn this equation into an easier equation, let's subtract 7 from both the left and right side.

Now our equation is much easier:

We have found that x=4.

To see this example in Algebra Calculator, type x+7=11. Feel free to try it now.