The price of a cheap backpack is $15 less than an expensive backpack. When Emily bought both, she pa

Discussion in 'Calculator Requests' started by math_celebrity, Jan 14, 2023.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    The price of a cheap backpack is $15 less than an expensive backpack. When Emily bought both, she paid $75. What is the cost of the cheap backpack?

    backpack cost = b
    Cheap backpack = b - 15

    The total of both items equals 75:
    b + b - 15 = 75

    Solve for b in the equation b + b - 15 = 75

    Step 1: Group the b terms on the left hand side:
    (1 + 1)b = 2b

    Step 2: Form modified equation
    2b - 15 = + 75

    Step 3: Group constants:
    We need to group our constants -15 and 75. To do that, we add 15 to both sides
    2b - 15 + 15 = 75 + 15

    Step 4: Cancel 15 on the left side:
    2b = 90

    Step 5: Divide each side of the equation by 2
    2b/2 = 90/2

    b = 45

    Cheap backpack = 45 - 15 = 30

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