Solving
Two Step
Equations
1)
Isolate the Variable Term –
Undo the operation that is there.
Addition: If a = b then a + c = b + c.
Subtraction: If a = b then a – c = b– c.
2)
Isolate the Variable –
Undo the operation that is there.
Multiplication: If a = b then ac = bc.
Division: If a = b and c ≠ 0 then a/c = b/c.
3)
Check by Substitution –
Plug in the value of the variable for the variable.
Substitution property: If x = y, then y can be
substituted for x in any expression
Example: x = 2 and x + 5 = 7, then 2 can be
substituted in x + 5 = 7 to obtain 2 + 5 = 7
8n + 7 = 31
8n + 7 = 31
-7 -7
b– 7
8n
8
= 24
8
-8 – 3x = 23
If a = b then a – 7 =
If a = b and c ≠ 0
then a/8 = b/8
n=3
Check:
8n + 7 = 31
8(3) + 7 = 31
If n = 3, then 3 can be substituted
for n in any expression