Classwork 4-3 Worksheet 1

Is the following statement never true, sometimes true, or always true? Explain.

a+c=b+d

Now you are given the information that

a=y

and

b=2x+3.

Use these equivalences to re-write the equation a=b.

Now you are given the additional information that

c=y

and

d=x-1.

(note, it is still the case that a=y and b=2x+3)

Use these equivalences to re-write the equation a+c=b+d.

Use these equivalences to re-write the equation a-2c=b-2d.

Emmy tells Terrance that she's discovered something incredible. She says that you can actually stack equations on top of each other add add them or subtract them, like this:

Is Emmy correct? Explain your thinking.