Hannah went to the school store to buy supplies and spent $16. She bought four more pencils than pens and two fewer erasers than pens. Pens cost $1.25 each, pencils cost $0.55 each, and erasers cost $0.75 each. If x represents the number of pens Hannah bought, write an equation in terms of x that can be used to find how many of each item she bought. Use your equation to determine algebraically how many pens Hannah bought.

The algebaraic equation required is :

2.55x + 0.7 = 16

The number of pens Hannah bought is 6

If :

x = number of pens

4 more pencils Than pens ; Number of pencils = x + 4

2 fewer erasers than pens ; number of erasers = x - 2

Total amount spent = $16

The total number of items bought is :

(x) + (x + 4) + (x - 2)

Multiplying by the cost of each :

1.25x + 0.55(x+4) + 0.75(x-2)

Hence, Total amount spent can be represented as :

1.25x + 0.55(x+4) + 0.75(x-2) = 16

1.25x + 0.55x + 2.2 + 0.75x - 1.50 = 16

2.55x + 0.7 = 16

The algebraic equation is : 2.55x + 0.7 = 16

The number of pens Hannah bought can be calculated thus :

2.55x + 0.7 = 16

2.55x = 16 - 0.7

2.55x = 15.30

x = 15.30 / 2.55

x = 6

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