Basic Algebra/Solving Equations/Solving Equations with Addition and Subtraction

LessonEdit

Zoey and Pual put three eggs on each side of a scale. When Zoey took an egg away on one side the scale, it tipped. When Pual took an egg from the other side of the scale, it is balanced again. The same thing can be used in math too.

What is ${\displaystyle y}$  in this equation?

${\displaystyle 2+y=7}$

We want to know what ${\displaystyle y}$  is, so we want to make ${\displaystyle y}$  by itself on one side of the equal sign.

First subtract 2 from both sides.

${\displaystyle 2-2+y=7-2}$

After we subtracted, ${\displaystyle y}$  is by itself and we can see that ${\displaystyle y}$  equals

${\displaystyle y=5}$

Example ProblemsEdit

Example 1

${\displaystyle 3+x-4=4}$

Add 4 to each side to get rid of the -4.

${\displaystyle 3+x-4+4=4+4}$

${\displaystyle 3+x=8}$

Subtract 3 from each side of the equation.

${\displaystyle 3+x-3=8-3}$

${\displaystyle x=5}$

Practice GamesEdit

put links here to games that reinforce these skills

Practice ProblemsEdit

1

${\displaystyle x+1=4}$

${\displaystyle x-1=4}$