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Solving Two-Step Equations

  • A two-step equation has two operations. You will need to cancel or undo each one by using its inverse operation.
  • Addition and subtraction are inverse operations. You can use the Addition Property of Equality and the Subtraction Property of Equality to undo the opposite operation.
  • Multiplication and division are inverse operations. You can use the Multiplication Property of Equality and the Division Property of Equality to undo the opposite operation.
  • Remember to work backwards from the order of operations. Undo addition and subtraction first, then multiplication and division.

Solving Two-Step Equations

4x − 3 = 81

  • 4x = 81 + 3
  • 4x = 84
  • x = [84/4]

x = 21

45 = [x/3] + 17

  • 45 − 17 = [x/3]
  • 28 = [x/3]

84 = x

11 + 8y = 59

  • 8y = 59 − 11
  • 8y = 48
  • y = [48/8]

y = 6

13x + 4 = 43

  • 13x = 43 − 4
  • 13x = 39
  • 4x = [39/13]

x = 3

− 2m − 63 = 47

  • − 2m = 47 + 63
  • − 2m = 110
  • m = [110/( − 2)]

m = − 55

− 5 = − 19 − [t/7]

  • − 5 + 19 = − [t/9]
  • 14 = − [t/9]
  • 14 ×9 = − t
  • 126 = − t

t = − 126

Duy begins with 16 gallons of gas in his car. His car uses 3 gallons of gas per hour of driving. He will stop to get more gas when there is 1 gallon left in the tank. After how many hours will Duy need to stop to refuel?

  • Let t = how long Duy drives
  • 16 gallons − (3 gallons per hour)t = 1 gallon
  • − 3t = 1 − 16
  • − 3t = − 15

t = 5 hours

A phone plan costs $ 0.45 per call and $ 0.10 per minute. You pay $ 2.30 for the call. Write and solve an equation to find the length of the call.

  • Let m = the length of the call.
  • $ 2.30 = $ 0.45 + $ 0.10m
  • $ 2.30 − $ 0.45 = $ 0.10m
  • $ 1.85 = $ 0.10m
  • m = $ 1.85 ÷$ 0.10

m = 18.5 minutes

You go to a county fair. It costs $ 11 to enter the fair, and it costs $ 3 for each ride at the fair. You spend $ 26 at the fair. How many rides did you ride?

  • Let r = number of rides you rode
  • $ 26 = $ 11 + $ 3r
  • $ 26 − $ 11 = $ 3r
  • $ 15 = $ 3r
  • r = $ 15 ÷$ 3

r = 5 rides

Eric buys one sandwich for $ 5.30 and 5 drinks. The total cost is $ 19.05. How much does one drink cost?

  • Let d = cost of one drink.
  • $ 5.30 + 5d = $ 19.05
  • 5d = $ 19.05 − $ 5.30
  • 5d = $ 13.75
  • d = $ 13.75 ÷5

d = $ 2.75

*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.

Answer

Solving Two-Step Equations

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

Mathematics: Pre Algebra