# More Than One of the Same Mystery Door

When you have finished this page, try the Equations 2 Quiz.

RECAP We learned in the last lesson about equations and the number behind the mystery door. We learned that by taking an equal amount from either side of an equation, we can come closer to finding out what the number is behind the mystery door. Now we will look at equations with more than one mystery door. In each case the same number will be behind each mystery door.

# 10

First one can take five from each side of the equation:

# 10 5

Now take a mystery door from each side of the equation. When that is done, we have our answer:

# 5

Let's go back to the original equation and see if this works:

# 10

 Algebra Main Page Positive & Negative Numbers Addition & Subtraction of Positive & Negative Numbers Multiplication of Positive & Negative Numbers Division of Positive & Negative Numbers Order of Operations Exponents Scientific Notation Equations 1 Equations 2 Equations 3 Equations 4 Equations 5 Equations 6 Equations 7 Equations 8 Equations 9 Algebra Videos