Question

Emily tried solving a two step equation for the variable. Interpret whether she made a mistake or not. If she did, describe what mistake she made and how she should have solved the problem. Prove your answer correct by showing all of your work.
Emily’s Work: On the photo.

Answer 1

-1 = z/3 - 7

Emily's Work:

-1 = z/3 - 7

-1(3)=z/3(3)-7

-3 = z - 7 

-3 -7 = z - 7 

z = -10

Right away without having to start at the beginning, I see that she has made a mistake at the 4th-5th line of work.


Instead of adding 7 to both sides, she subtracts it and still leaves it in and doesn't fully finish the equation, as it would really be z-7 = -10

In order to solve it, follow these steps:

Rewrite the initial equation as follows:

x/3 - 7 = -1 

Multiply both sides by 3
x/3(3)-7(3)=-1(3)

x - 21 = -3

Add 21 to both sides

x = 18