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