1. One step equation with Addition and Subtraction

2. Introduction What is an equation?
An equation is a mathematical statement that
shows 2 quantities are equal. An equation contains
an equal sign.
12 – 3 = 9 Numerical
3a = 30 Algebraic

3. = 29 10+19 An Equation is like a balance scale.
Everything must be equal on both sides. = 29
10+19

4. Steps for Solving One-Step Equations
1) Get the variable on one side of the equation.
2) You always perform the same operation to
both sides of an equation.
3) To undo an operation you perform its opposite
operation to both sides of the equation.

5. Opposite operations
The opposite of add is
SUBTRACT
The opposite of subtract is
ADD
The opposite of multiply is
DIVIDE
The opposite of divide is
MULTIPLY

6. Solving Equations Using Addition or Subtraction:
Rule 1: If a number has been added to the variable, subtract that number from both sides of the equation. Rule 2: If a number has been subtracted from the variable, add that number to both sides of the equation.

7. Example 1: Solve x + 7 = 15
Solution:
Equals x = 15
RHS
LHS
Variable/
Unknown x = 15
Constants
Get the variable on one side of the equation.
We keep variable x on the left handside(LHS) and move constant to the right handside(RHS) x =
By rule 1, 7 is added to the
variable x, so subtract 7 from
both sides of the equation x = 8
By integer rule, if numbers
have different sign,
subtract the numbers and put sign of bigger number
Ans: x = 8

8. Example 2: Solve x + 10 = -6
Solution:
Equals x = -6
RHS
LHS
Variable/
Unknown x = -6
Constants
Get the variable on one side of the equation.
We keep variable x on the Left Handside(LHS) and move constant to the Right Handside(RHS)
By integer rule, if numbers
have different sign,
subtract the numbers and put sign of bigger number x =
By rule 1, 10 is added to the
variable, so subtract 10 from
both sides of the equation x =
-16
By integer rule, if numbers
having same sign, we
add the numbers and put the same sign
Ans: x = -16

9. Example 3: Solve n – 2.5 = 10
Solution:
Equals = n 10
RHS
LHS
Variable/
Unknown n = 10
Constants
Get the variable on one side of the equation.
We keep variable n on the Left Handside(LHS) and move constant to the Right Handside(RHS) n =
By rule 2, 2.5 is subtracted
from the variable, so add 2.5
to both sides of the equation n =
12.5
By integer rule, if numbers
have same sign,
add the numbers and put sign of bigger number
Ans: n = 12.5

10. Example 4: Solve n - 7 = -5
Solution:
Equals
n - 7 = -5
RHS
LHS
Variable/
Unknown n = -5
Constants
Get the variable on one side of the equation.
We keep variable n on the Left Handside(LHS) and move constant to the Right Handside(RHS) n =
By rule 2, 7 is subtracted
from the variable, so add 7
to both sides of the equation
By integer rule, if numbers
have different sign,
subtract the numbers and put sign of bigger number n = 2
Ans: n = 2

11. Try these
m + 9 = 12
x – 8 = -14