How To Solve Two Step Equations with Addition

How To Solve Two Step Equations with Addition & Subtraction

Let’s Take a Look at Tim & Moby’s Video This is an animated video that will give you a brief overview of two-step equations and what they are used for. Click here to see the Brain Pop Video on Two Step Equations Click Log in Username: shelbyc Password: shelbyc 1

Let’s Start With Some Variable A symbol in place of a number you don't yet know. Coefficient The numerical factor in a term. Equation Shows two math expressions as equal. Inverse Operation The opposite order of operation of the equation

Can any letter be used as a variable? YES! Typically x and y are used but ANY letter can be used for a variable. 2 x 4 m variable coefficient 9 a 6 b variable coefficient 7 p variable coefficient 3 n variable coefficient

Let’s take a look at subtraction equations first……

Steps to Solve Two-Step Equations Simplify using the inverse of addition or subtraction. Simplify further by using the inverse of multiplication or division. 3 w - 2 = 22 The equation above is a subtraction equation. The inverse of subtraction is…. ADDITION.

Add 2 to each side of the equation since addition is the inverse The equation is now a multiplication equation 3 w-2 = 22 Step One 3 w – 2 = 22 +2 +2 3 w = 24 Step Two 3 w = 24 3 3 w=8 Divide 3 on each side since division is the inverse The solution is 8.

Add 12 to each side of the equation since addition is the inverse The equation is now a multiplication equation Step One 4 m = 60 4 4 m = 15 Step Two 4 m – 12 = 48 +12 4 m = 60 Divide 4 on each side since division is the inverse operation The solution is 15.

Problem Solving Mrs. Stevens earns $18 per hour at her job. She had $171 after paying $9 for subway fare. Write and solve an equation to find how many hours Mrs. Steven worked. Equation 18 x + 9 = 171 Solve Words Amount earned times the number of hours worked plus the amount spent Variable 18 x + 9 = 171 -9 -9 Subtract 9 from both sides 18 x = 162 The equation is now multiplication 18 18 Divide both sides by 18 x=9 Let x represent the number of hours Mrs. Stevens worked 9 hours.

Let’s take a look at addition equations next….

Subtract 14 from each side of the equation since subtraction is the inverse The equation is now a multiplication equation Step One 5 n = 25 5 5 n=5 Step Two 5 n + 14 = 39 -14 5 n = 25 Divide 5 on each side since division is the inverse operation The solution is 5.

Step One 9 k = 81 9 9 k=9 Step Two 9 k + 36 = 117 -36 Subtract 36 from each side of the equation since subtraction is the inverse 9 k = 81 The equation is now a multiplication equation Divide 9 on each side since division is the inverse operation The solution is 9.

Problem Solving At the local fun center, a hamburger meal costs $4. 50 and each ride costs $2. 50. If you have $22. 00, how many rides can you go on if you but a meal? Equation 4. 50 + 2. 50 r = $22. 00 Solve Words Cost of hamburger meal plus cost of 1 ride times number of rides equals $22. 00 Variable Let r represent the number of rides 4. 50 + 2. 50 r = 22. 00 -4. 50 2. 50 r = 17. 50 2. 50 r=7 You can ride 7 rides. Subtract 4. 50 from both sides Step 2 multiplication equation Divide 2. 50 on both sides