Question

1 What is a rule that you can you solve in addition equation without using a model?2 How can the number family 3,4,7 help you to solve the equation 3+x=7?

Answer 1

1.-

In addition equations, we can solve for a variable by subtracting the same number on both sides of the equation.

This is in order to leave the variable we want to solve for alone on one side of the equation.

2.-

The addition equation we have is:

`3+x=7`

Using the rule of part 1: subtract the same number on both sides to solve for x.

In this case, we have to subtract 3 to both sides:

`3-3+x=7-3`

On the left side, 3-3 cancel each other and we are left only with x:

`x=7-3`

And on the right side, 7-3 is equal to 4:

`x=4`

Thus, the use of the number family is:

3 is the number we subtract to both sides.

7 is the number to which we subtract 3.

4 is the result of the subtraction.